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In games that follow the [[Tetris Guideline]], especially with regard to the [[hold piece]] feature and the [[Random Generator]] that deals tetrominoes in sets of 7, it appears that the player can play forever by mentally dividing the playfield into three heaps, each of which can be considered a separate well. All S, Z, and T tetrominoes go to one side, and L, J, and O tetrominoes go to the other. I tetrominoes go to the center.
[[Image:Playing forever like CT.gif|right|frame|A 140-tetromino run of this strategy.]]
{{pfstart}}
The following outlines a method of playing forever given the following conditions, which apply in many [[Tetris Guideline|''Tetris'' products since 2001]]:
{{pfrow| |Z| | | |I| | | | }}
*the [[Random Generator]] is used to generate piece sequences
{{pfrow|Z|Z|S| | |I|L|O|O|J}}
*the game has the [[Hold]] feature
{{pfrow|Z|T|S|S| |I|L|O|O|J}}
*at least 3 [[piece preview]]s are available
{{pfrow|T|T|T|S| |I|L|L|J|J}}
 
{{pfend}}
== Standard procedure ==
[[Image:Polyomino.net Playing forever.png|right|frame|The 10x56 cell tiling that this method creates]]
 
The general method is achieved by dividing the screen into self contained sections as shown below. Specifically, the 4 left columns, the 4 right columns, and the 2 middle columns will be treated as distinct regions, with specific pieces assigned exclusively to each region. Because the random generator provides strings of bags containing each of the 7 pieces in a random order, it is possible to construct a strategy around the relatively small variation, with looping patterns.
 
S, T, and Z will be placed to the left, L, J, and O will be placed to the right, and I pieces will fill the middle.
 
<playfield>
Z  I   
ZZS  ILOOJ
ZTSS ILOOJ
TTTS ILLJJ
</playfield>
 
=== The S, T, and Z piece loop ===
{| style="float:left"
|<playfield>
STTT     
SSTZ     
SSZZ     
SSZZ     
TSZZ     
TTZT     
TZTT     
ZZST     
ZZSS     
ZZSS     
ZTSS     
TTTS     
</playfield>
|}
This pattern loops after 4 bags of pieces. Depending on the order of the pieces for each bag, you may need to use [[Hold]] to force a piece to come last. Piece previews are technically not required to play this pattern.
 
<br clear="left" />
 
The Z piece must drop after T, so use Hold to change the order if necessary:
<playfield>
Z       
ZZS     
ZTSS     
TTTS     
GGGG     
</playfield>
 
The T piece must not drop first, so use Hold to change the order if necessary:
{|
|<playfield>
         
  T     
ZTT     
ZZST     
ZGSS     
GGGS     
</playfield>
Option 1
|<playfield>
T       
TT       
TZ       
ZZS     
ZGSS     
GGGS     
</playfield>
Option 2
|}
 
The T piece must land diagonally adjacent to the other T, so use Hold to change the order if necessary:
{|
|<playfield>
S       
SS Z     
TSZZ     
TTZG     
TGGG     
GGGG     
</playfield>
Option 1 (needs<br>
T before S)
|<playfield>
S       
SS Z     
GSZZ     
GGZT     
GGTT     
GGGT     
</playfield>
Option 2 (needs<br>
T before Z)
|}
 
The T piece must drop last, so use Hold to change the order if necessary:
<playfield>
         
STTT     
SSTZ     
GSZZ     
GGZG     
</playfield>
 
=== The L, J, and O piece loop ===
This pattern loops after a single bag of pieces. Depending on the order of the pieces, you will need to use a different construction. At least 5 previews are required to choose the appropriate construction. Alternatively, it is possible to use 3 previews and clever use of Hold (that does not conflict with the STZ loop's Hold needs) to choose an approriate construction using some advanced techniques.
 
O first (OJL, OLJ):
<playfield>
      JJLL
      JOOL
      JOOL
</playfield>
O last (JLO, LJO):
<playfield>
      LOOJ
      LOOJ
      LLJJ
</playfield>
JOL: (mirror for LOJ)
{|
|<playfield>
      JJ 
      J 
      J 
</playfield>
Drop J
|<playfield>
      JJ 
      J OO
      J OO
</playfield>
Soft-drop O
|<playfield>
      JJ 
      JOO
      JOO
</playfield>
Slide O
|<playfield>
      JJLL
      JOOL
      JOOL
</playfield>
Drop L
|}
 
==== Advanced techniques for when only 3 previews are available ====
Worst case bag distributions such as H?XX?X? and H?XXX?? deserve a special mention. The first piece 'H' denotes a piece which must be placed in Hold in order to follow the STZ loop procedure. Pieces from the LJO loop are denoted by '?', and the remaining pieces are denoted by 'X'. Using 3 previews and Hold, it is only possible to see the first 4 pieces of the bag before the second piece enters the screen. This means you only see H?XX, and only know the first piece of the LJO loop. Because H must be put in Hold, you are forced to make a decision without knowing the order of the rest of the LJO loop. If the O comes first, you can follow the procedure above without problems. The rest of the time you will run into complications like this:
 
Impossible O placement (eg. HLXXJXO, HLXXXJO):
<playfield>
      JJLL
      J  L
      J  L
</playfield>
Impossible J placement (eg. HLXXOXJ, HLXXXOJ):
<playfield>
      LOO
      LOO
      LL 
</playfield>
 
When L or J come first it is impossible to determine which LJO pattern to use without knowing the order of the final 2 pieces. The solution to this problem is to wait until the first L or J piece enters the screen before making a decision. With the held piece, active piece, and 3 previews, you now see 5 pieces into the bag. This allows you to tell the LJO piece order for the case of H?XX?X?. However, in the case of H?XXX?? the order remains unknown. With this final worst case, the STZ loop is guaranteed to be finished before the second and third pieces of the LJO loop are dealt. This means Hold is available! You can start building whichever pattern you prefer, and use Hold to change the order of the final 2 pieces as necessary.
 
==== Tricky starts when only 3 previews are available ====
 
There is a worst case start that only complicates the very first bag when playing forever. With a sequence such as ?HXX?X? you can see a maximum of 4 pieces into the bag as you place the first piece. It is impossible to Hold the first piece (part of LJO) because the second piece (part of SZT) must be held. Additionally, because the second last piece is also part of the STZ loop, Hold cannot be used to change the order of the the final 2 LJO pieces as discussed above. So a decision must be made with only the first 4 pieces of the bag known. In this case, the solution is to note that the STZ pattern in the previous section requires the Z to be placed last. However, the mirror STZ pattern is equally feasible, and would require the S to be placed last. Because you have these 2 options, it is impossible that the first piece dealt for the STZ loop is required to be placed last. The worst case is now ?SZX?X?, which can be expressed as ?XHX?X?. By holding the first piece, placing the second, and holding the third, you can now see the first 6 pieces of the bag. This then allows you to choose an appropriate LJO pattern.
 
It should be noted that this affects only the very first bag of playing forever, which is not to be confused with the first bag of every 20-bag loop of playing forever. On subsequent loops, the first piece of the first bag is already in Hold. You can see the first 5 pieces of ?HXX?X? after you put H on Hold, which makes the first piece active, and sums to 5 with the 3 previews. It is only a problem for the first bag of the game because the player is restricted to a maximum of one use of Hold before placing a piece.
 
=== The I piece loop ===
This pattern loops every 2 bags. No use of Hold or piece previews is required. The player must simply alternate putting the I tetromino in columns 5 and 6 to reap tetrises.
{|
|<playfield>
    I   
    I   
    I   
    I   
</playfield>
|<playfield>
    GI   
    GI   
    GI   
    GI   
</playfield>
|}
Notice that the alternate JOL method will work only if the first I tetromino of the loop is placed away from the JLO heap.
 
== Balancing the Stacks ==
Since the loops have a cycle of 4, 1, and 2 bags respectively, after playing 4 bags they will all be flat. However, the I loop will have only placed 8 rows compared to the 12 rows placed by both the STZ and LJO loops.
{|
|- valign="top"
|<playfield>
         
         
         
STTT  LOOJ
SSTZ  LOOJ
SSZZ  LLJJ
SSZZ  JJLL
TSZZIIJOOL
TTZTIIJOOL
TZTTIILOOJ
ZZSTIILOOJ
ZZSSIILLJJ
ZZSSIILOOJ
ZTSSIILOOJ
TTTSIILLJJ
</playfield>
The rows stacked <br> after 4 bags.
|<playfield>
         
         
         
STTT  LOOJ
SSTZ  LOOJ
SSZZ  LLJJ
SSZZ  JJLL
----------
----------
----------
----------
----------
----------
----------
----------
</playfield>
Though of course, <br> lines have cleared.
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
STTT  LOOJ
SSTZ  LOOJ
SSZZ  LLJJ
SSZZ  JJLL
</playfield>
Leaving us with a <br> surplus.
|}
 
In order to offset this balance, it is necessary to change strategy. Continue to do the standard STZ loop, while using the following LO and IJ loops.
 
=== The L, O piece loop ===
This pattern loops after 2 bags of pieces. Order is not important, and therefore neither Hold nor piece previews are strictly required for it.
 
{|
|<playfield>
         
        L
      OOL
      OOLL
</playfield>
|<playfield>
      OOLL
      OOGL
      GGGL
      GGGG
</playfield>
|}
 
=== The I, J piece loop ===
This pattern loops after 2 bags of pieces. Order is not important, and therefore neither Hold nor piece previews are strictly required for it.
 
JIIJ:
{|
|- valign="top"
|<playfield>
         
         
GGGG  GGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG JGGGG
GGGG JGGGG
GGGGJJGGGG
</playfield>
|<playfield>
         
         
GGGGJJGGGG
GGGGJGGGGG
GGGGJGGGGG
GGGGIGGGGG
GGGGIGGGGG
GGGGIGGGGG
GGGGIGGGGG
GGGGGGGGGG
</playfield>
|}
 
Because of line clears, the order is not very important. Even if you place pieces in the opposite order than what is shown, the net change in screen geometry will be the same:
{|
|- valign="top"
|<playfield>
         
         
GGGG  GGGG
GGGG JGGGG
GGGG JGGGG
GGGGJJGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
</playfield>
|<playfield>
         
         
GGGG  GGGG
GGGG JGGGG
GGGG JGGGG
----------
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
</playfield>
|<playfield>
         
         
         
GGGGJJGGGG
GGGGJJGGGG
GGGGJJGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
</playfield>
|<playfield>
         
         
         
----------
----------
----------
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
</playfield>
|}
 
=== Putting it all together ===
If you play the standard method for 12 bags, the balancing method for 4 bags, and finally the reverse balancing method (with LO on the left and STZ on the right) for 4 bags, then you will clear the entire screen allowing you to start over again and play indefinitely.
 
{|
|- valign="top"
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
         
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
</playfield>
The net result of <br> 12 bags stacked <br> the standard way.
|<playfield>
STTT     
SSTZ     
SSZZ     
SSZZ     
TSZZ  OOLL
TTZT  OOLL
TZTT  OOLL
ZZST  OOLL
ZZSSJJOOLL
ZZSSJIOOLL
ZTSSJIOOLL
TTTSIIOOLL
GGGGIIGGGG
GGGGIJGGGG
GGGGIJGGGG
GGGGJJGGGG
GGGGJJGGGG
GGGGJIGGGG
GGGGJIGGGG
GGGGIIGGGG
GGGGIIGGGG
GGGGIJGGGG
GGGGIJGGGG
GGGGJJGGGG
</playfield>
The rows stacked <br> after 4 bags of <br> balanced stacking.
|<playfield>
STTT     
SSTZ     
SSZZ     
SSZZ     
TSZZ  OOLL
TTZT  OOLL
TZTT  OOLL
ZZST  OOLL
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
</playfield>
Of course, <br> line clears <br> have actually...
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
STTT     
SSTZ     
SSZZ     
SSZZ     
TSZZ  OOLL
TTZT  OOLL
TZTT  OOLL
ZZST  OOLL
</playfield>
...kept things <br> realistically short.
|}
 
{|
|- valign="top"
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
GGGG     
GGGG     
GGGG     
GGGG     
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
</playfield>
Where we left off.
|<playfield>
         
         
         
OOLLJJTTTZ
OOLLJISTZZ
OOLLJISSZZ
OOLLIISSZZ
OOLLIISSZT
OOLLIJTSTT
OOLLIJTTST
OOLLJJTZSS
GGGGJJZZSS
GGGGJIZZSS
GGGGJIZZTS
GGGGIIZTTT
GGGGIIGGGG
GGGGIJGGGG
GGGGIJGGGG
GGGGJJGGGG
</playfield>
4 bags balancing <br> the other side.
|<playfield>
         
         
         
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
</playfield>
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
</playfield>
Back to <br> square one.
|}
===The Final Bag===
The final bag requires some special consideration. Because the sides are getting low, the J piece will not necessarily clear. So I must come before J in order to follow the pattern. You can't rely on using Hold for this as a worst case scenario (eg. TJIxxxx) would also require you to Hold the T. To deal with this problem, you can follow the procedure below.
{|
|- valign="top"
|<playfield>
         
         
         
         
         
         
         
    I   
    I   
    I   
    I   
    JJ   
  G JG   
GGG JG  g
GGGG GG GG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
GGGGGGGGGG
</playfield>
Stack the I on <br> top of the J.
|<playfield>
         
         
         
         
         
         
         
    I   
    I   
    I   
    I   
OOLLJJTTTZ
OOGLJGSTZZ
GGGLJGSSZg
GGGG GGSGG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
GGGGGGGGGG
</playfield>
Play the <br> remainder.
|<playfield>
         
         
         
         
         
         
         
    I   
    I   
    I   
    I   
----------
----------
----------
GGGG GGSGG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
----------
</playfield>
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
    I   
    I   
    I   
    I  
GGGG GGSGG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
</playfield>
The end of the <br> 20-bag loop.
|}
 
But after the first bag of the next loop, we're exactly where we expect to be:
{|
|- valign="top"
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
    G   
    G   
    G   
    G   
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
</playfield>
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
Z  G   
ZZS  GJJLL
ZTSS GJOOL
TTTS GJOOL
GGGGIGGGGG
GGGGIGGGGG
GGGGIGGGGG
GGGGIGGGGG
</playfield>
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
Z  G   
ZZS  GJJLL
ZTSS GJOOL
TTTS GJOOL
----------
----------
----------
----------
</playfield>
|<playfield>
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
Z  G   
ZZS  GJJLL
ZTSS GJOOL
TTTS GJOOL
</playfield>
|}
 
 
== 5 Bag Solution ==
A shorter but far more complicated algorithm for Playing Forever in 5 bags was discovered by QM in 2014. It requires 4 piece previews to guarantee success.
 
This is the minimum possible Playing Forever loop, as a Perfect Clear must use 35 pieces (as the well is 10x10). To avoid parity issues with 5 T pieces, the Bag 2 T is used to clear a single and skim.
 
=== First Bag ===
Build this structure whenever possible.
<playfield>
Z  IIII 
ZZS JJLL 
ZTSSJOOL 
TTTSJOOL 
</playfield>
If necessary, the JILO square can be built in a different order as long as it remains a 4x4 square.
 
If this structure was impossible (this is rare), place the I to the right.
<playfield>
Z      I
ZZS JJLL I
ZTSSJOOL I
TTTSJOOL I
</playfield>
=== Second Bag ===
The second bag is built differently based on whether the JILO square was completed successfully or not. In either case, the J, L, O, S, and Z pieces are placed identically, like this:
<playfield>
    LOOJ 
Z  LOOJ 
ZZS LLJJ 
ZZSSIIII 
ZZSSJJLL 
ZTSSJOOL 
TTTSJOOL 
</playfield>
Again, the J, L, and O can be flipped if necessary.
 
The I and T pieces will be placed differently based on the completion of the JILO square in Bag 1.
==== Case A: The JILO square in Bag 1 was completed. ====
 
The T and I pieces should be used to line clear, in this order:
 
<playfield>
    LOOJ 
Z  LOOJ 
ZZS LLJJ 
ZZSSIIII 
ZZSSJJLLT
ZTSSJOOLTT
TTTSJOOLT
</playfield>
 
<playfield>
    LOOJ 
Z  LOOJ 
ZZS LLJJ I
ZZSSIIII I
ZZSSJJLLTI
TTTSJOOLTI
</playfield>
 
Leaving the end result of the second bag as this:
 
<playfield>
    LOOJ 
Z  LOOJ 
ZZS LLJJ I
ZZSSIIII I
</playfield>
 
The T and I pieces can be placed at any time as long as Hold is used to ensure that the T is placed before the I.
 
==== Case B: The I piece in Bag 1 was placed to the right. ====
 
The I piece should be placed first using Hold to perform a Tetris line clear.
 
<playfield>
Z  LOOJ 
ZZS LOOJ 
ZZSSLLJJII
ZZSSJJLLII
ZTSSJOOLII
TTTSJOOLII
</playfield>
 
Then, the T piece should be placed in one of these two ways, dependent on the order of Bag 3:
 
T facing to the left
<playfield>
        T
Z  LOOJTT
ZZS LOOJ T
</playfield>
 
T facing to the right
<playfield>
        T
Z  LOOJTT
ZZS LOOJT
</playfield>
 
The T and I pieces can be placed at any time as long as Hold is used to ensure that the I is placed before the T.
 
===== Determining the direction of the T =====
With Hold and 4 piece previews, you can see the first 5 pieces of the third bag when placing the T. Based on the order of STZ in the third bag, decide which direction the T should be placed in using the first rule that applies:
 
1) If TZ comes first in {STZ}, the first two pieces of {IJLO} are OI, and Z comes before I, place facing left.
 
2) If T comes first, place facing right.
 
3) If Z comes first, place facing left.
 
4) If S comes first and is the only STZ piece in all 5 visible pieces, place facing right.
 
5) If S comes first and T comes second, place facing right.
 
6) If none of the previous rules apply, place facing left.
 
=== Bag 3 ===
This bag is highly situational based on the order of the pieces.
 
==== Case A: The JILO square in Bag 1 was successfully completed. ====
If this is the case, place the pieces like this. Make sure to use Hold on Z to be sure it is possible.
<playfield>
    JJLL 
ZZ  JOOL 
TZZ JOOL 
TTS GGGGI
TGSSGGGGI
GGGSGGGGIG
GGGGGGGGIG
</playfield>
 
==== Case B: The JILO square in Bag 1 was not successfully completed. ====
If this is the case, the S, T, and Z pieces should be placed in one of these two ways:
 
<playfield>
ZZ       
TZZ     
TTS    T
TGSSGGGGTT
GGGSGGGGT
</playfield>
<playfield>
T       
TT       
TZ       
ZZS      T
ZGSSGGGGTT
GGGSGGGG T
</playfield>
 
Decide which one to build based on the T placement from Bag 2.
 
The I, J, L, and O pieces should be assembled to form a 4x4 square. Note that based on the order, this square can be assembled in whatever arrangement is necessary, including sideways, as long as it forms a square. These are just a few examples of how it could be built.
 
<playfield>
    JJLL
ZZ  JOOL 
TZZ JOOL 
TTS IIIIG
TGSSGGGGGG
GGGSGGGGG
</playfield>
<playfield>
    IIII
ZZ  JOOL 
TZZ JOOL 
TTS JJLLG
TGSSGGGGGG
GGGSGGGGG
</playfield>
<playfield>
    IJJJ
ZZ  IJOO 
TZZ ILOO 
TTS ILLLG
TGSSGGGGGG
GGGSGGGGG
</playfield>
 
This can be done without hold unless the order is OIJL or OILJ. In these cases Hold should be used either to modify the piece order to IO{JL} or to O{JL}I. Decide which of these is necessary based on when in the bag Hold is used for the S, T, and Z pieces. This will rarely happen, though.
 
=== Bag 4 ===
The I, J, L, and O pieces in Bag 4 are placed into the holes left from the previous bags.
 
<playfield>
JJJIGGGGOO
GGJIGGGGOO
GGGIGGGGLL
GGGIGGGGGL
GGGGGGGGGL
</playfield>
<playfield>
GLLIGGGGOO
GGLIGGGGOO
GGLIGGGGJJ
GGGIGGGGJG
GGGGGGGGJG
</playfield>
 
Occasionally, the O piece may be placed in before the J or L on the corresponding side, as long as the I and J/L piece are already in.
 
In some cases, an I-spin may be necessary if the I shows up late in the sequence.
 
==== Placing the S, T, and Z ====
The first of S/Z and T should be placed like this:
 
<playfield>
    T   
    TT   
    TSS 
    SS   
</playfield>
<playfield>
    T   
    TT   
  ZZT   
    ZZ   
</playfield>
 
The last S/Z piece should be held to the end. 5 pieces of Bag 5 can then be seen in Hold + 4 piece previews. If T comes first in Bag 5's S, T, and Z, then place the S/Z piece like this:
 
<playfield>
    T   
    TT   
    TSSZZ
    SS  ZZ
</playfield>
<playfield>
    T   
    TT   
SSZZT   
SS  ZZ   
</playfield>
 
If S or Z come first in Bag 5's S, T, and Z, place the S/Z piece like this:
 
<playfield>
    TZZ 
    TTZZ 
    TSS 
    SS   
</playfield>
<playfield>
  SST   
  SSTT   
  ZZT   
    ZZ   
</playfield>
 
=== Bag 5 ===
 
The T piece and one of the S/Z pieces are placed like this:
<playfield>
    TZZ  T
    TTZZTT
    TSSZZT
    SS  ZZ
</playfield>
The other STZ piece is held until the end.
 
The 4x4 square on the side is filled with the I, J, L, and O pieces (This can be done in any way as long as the area is filled)
 
<playfield>
IIIITZZ  T
JJLLTTZZTT
JOOLTSSZZT
JOOLSS  ZZ
</playfield>
<playfield>
IIIITZZ  T
JOOLSS  ZZ
</playfield>
 
The final piece is placed in with an S/Z spin.
<playfield>
IIIITZZSST
JOOLSSSSZZ
</playfield>
 
== Open questions ==
Adapting this method to the following situations is left as an exercise for the reader:
*All tetris line clears
*High [[Drop#Gravity|gravity]] (solved)
*No [[hold piece]]
*14-piece bag randomizer
 
<!-- == Loop without Perfect Clear ==
 
[[File:Forever-standard.gif|right|frame|A 70 pieces run of this strategy.]]
 
The following technique is easier to learn as the method above but doesn't loop back to an empty playfield. It functions very similar but needs a little more requirements:
 
* [[Random Generator]], also known as 7-bag randomizer
* [[Hold]] feature
* 5 [[Piece preview]]s (if not specified otherwise)
* Sonic Drop respectively Soft Drop
* high enough playfield
 
In the first bag, a [[SRS#Wall Kicks|SRS wall kick]] may also be required to move the T piece below the S piece. Like above, the field is devided into 3 sections but their positions never change.
 
* First, we have a 4-column-wide section for S, Z and T pieces. The first T piece is placed horizontally on the left side. The left 2 columns are reserved for Z pieces and the right 2 columns for S pieces. T pieces are usually put in hold until another T piece shows up. In this case, the 2 T pieces are placed above each other vertically.


== S, T, and Z tetrominoes ==
* Then, we have a 2-column-wide section for I pieces. Every 10 bags (70 pieces), 2 T pieces and 2 J pieces are dropped on this section in a way that they clear exactly one line.
Imagine playing Tetris in a 4-block-wide well, with a randomizer that deals bags containing one S, one T, and one Z tetromino. Each round would consist of three tetrominoes, and in each round the player would have one of the following six different bags to deal with: STZ, SZT, TSZ, TZS, ZST, and ZTS.  For each shape of the well floor, I describe how each bag would be played. When instructed to hold a tetromino and use it later, the player should hold the tetromino and then bring it back out at the seam between bags.


=== Flat ===
* Finally, there's the 4-column-wide section for L, J and O pieces. The 5 previews are needed to know the order of L, J and O in the bag. If the O piece shows up between L and J, then the piece that comes first (L resp. J) is dropped vertically with its head up and the O piece is moved below it with Sonic Drop.
{{pfstart}}
{{pfrow| | | | | | | | | | }}
{{pfrow|G|G|G|G| | | | | | }}
{{pfend}}
Becomes 1210 or 0121.


TZS and TSZ can be played either of two ways:
{|
{|
|{{pfstart}}
| width=16 |
{{pfrow| |Z| | | | | | | | }}
| {{pfstart}}
{{pfrow|Z|Z|S| | | | | | | }}
{{mrow4| | |Z| }}
{{pfrow|Z|T|S|S| | | | | | }}
{{mrow4| | |Z|Z}}
{{pfrow|T|T|T|S| | | | | | }}
{{mrow4| | |T|Z}}
{{pfrow|G|G|G|G| | | | | | }}
{{mrow4| |S|T|T}}
{{mrow4|S|S|T|T}}
{{mrow4|S|S|T|T}}
{{mrow4|S|S|Z|T}}
{{mrow4|S|S|Z|Z}}
{{mrow4|S|S|Z|Z}}
{{mrow4|S|T|Z|Z}}
{{mrow4|T|T|T|Z}}
{{pfend}}
| width=20 |
| {{pfstart}}
{{mrow2| | }}
{{mrow2| |J}}
{{mrow2| |J}}
{{mrow2|J|J}}
{{mrow2| |T}}
{{mrow2|T|T}}
{{mrow2| |T}}
{{mrow2|I|I}}
{{mrow2|I|I}}
{{mrow2|I|I}}
{{mrow2|I|I}}
{{pfend}}
{{pfend}}
|{{pfstart}}
| width=20 |
{{pfrow| | |S| | | | | | | }}
| {{pfstart}}
{{pfrow| |Z|S|S| | | | | | }}
{{mrow4| | | | }}
{{pfrow|Z|Z|T|S| | | | | | }}
{{mrow4|L|L|O|O}}
{{pfrow|Z|T|T|T| | | | | | }}
{{mrow4|L|L|O|O}}
{{pfrow|G|G|G|G| | | | | | }}
{{mrow4|L|L|O|O}}
{{mrow4|L|L|O|O}}
{{mrow4|J|J|L|L}}
{{mrow4|J|O|O|L}}
{{mrow4|J|O|O|L}}
{{mrow4|L|O|O|J}}
{{mrow4|L|O|O|J}}
{{mrow4|L|L|J|J}}
{{pfend}}
{{pfend}}
|}
|}


STZ:
Every 10 bags, 28 pieces are dropped on the first section (10 S, 10 Z, 8 T), 28 pieces as well on the second section (10 O, 10 L, 8 J) and 14 pieces on the third section (10 I, 2 T, 2 J). This makes 28 cleared lines (6 Tetrises and 4 Singles) and no section is growing in respect of the other sections. Thus, this technique loops every 10 bags. Here's a brief description how one can proceed to loop back to the playfield where the first bag was already placed. In practice however, it is probably better to stack higher and use O pieces in the I section instead of J. In this case, the technique loops every 20 bags.
{|
 
|{{pfstart}}
{| border=1 cellspacing=0
{{pfrow| | | | | | | | | | }}
|-
{{pfrow| | |S| | | | | | | }}
! width=80 align=center | bags 1 & 2
{{pfrow| | |S|S| | | | | | }}
| width=200 style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Put first I on top of existing I and use second I to score a Tetris.
{{pfrow| | | |S| | | | | | }}
| {{sstart}}
{{pfrow|G|G|G|G| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  | S|  |  |  |  |  |  |  }}
{{srow|  |  | S| S|  |  |  |  |  |  }}
{{srow|  |  | T| S|  |  | J| J| L| L}}
{{srow|  | Z| T| T|  | I| J| O| O| L}}
{{srow| Z| Z| T| T|  | I| J| O| O| L}}
{{srow| Z| Z| T| T|  | I| L| O| O| J}}
{{srow| Z| Z| S| T|  | I| L| O| O| J}}
{{srow| Z|-Z| S| S| I|-I| L| L| J| J}}
{{srow|-Z|-Z|-S| S| I|-I|-J|-J|-L|-L}}
{{srow|-Z|-T|-S|-S| I|-I|-J|-O|-O|-L}}
{{srow|-T|-T|-T|-S| I|-I|-J|-O|-O|-L}}
{{pfend}}
|-
! align=center | bags 3 & 4
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Put first I on top of existing I and use second I to score a Tetris.
| {{sstart}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  | T|  |  |  |  |  |  |  |  }}
{{srow| T| T| S| | | L| O| O| J}}
{{srow| T| T| S| S| | | L| O| O| J}}
{{srow| T| T| S| S|  |  | L| L| J| J}}
{{srow| T| Z| S| S|  | I| L| O| O| J}}
{{srow| Z| Z|-S| S|  | I| L| O| O| J}}
{{srow| Z| Z|-S|-S|  | I| L| L| J| J}}
{{srow| Z| Z|-T|-S|  | I|-J|-J|-L|-L}}
{{srow| Z|-Z|-T|-T| I|-I|-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T| I|-I|-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-T| I|-I|-L|-O|-O|-J}}
{{pfend}}
|-
! align=center | bags 5 & 6
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Score a Tetris with first I.
| {{sstart}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  | T|  |  |  |  |  |  |  }}
{{srow|  |  | T| T|  |  |  |  |  |  }}
{{srow|  |  | T| T|  |  | J| J| L| L}}
{{srow|  | Z| T| T|  |  | J| O| O| L}}
{{srow| Z| Z| S| T|  |  | J| O| O| L}}
{{srow| Z| Z| S| S|  |  | J| J| L| L}}
{{srow| Z| Z| S| S|  |  | J| O| O| L}}
{{srow| Z|-T| S| S|  | I| J| O| O| L}}
{{srow|-T|-T|-S| S|  | I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S|  | I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S|  | I|-L|-L|-J|-J}}
{{srow|-T|-Z|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-S| I|-I|-L|-L|-J|-J}}
{{srow|-Z|-Z|-T|-S| I|-I|-J|-J|-L|-L}}
{{pfend}}
{{pfend}}
Drop S
|-
|{{pfstart}}
! align=center | bags 7 & 8
{{pfrow| | | | | | | | | | }}
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Score a Tetris with first I.
{{pfrow|T| |S| | | | | | | }}
| {{sstart}}
{{pfrow|T|T|S|S| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|T| | |S| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|G|G|G|G| | | | | | }}
{{srow|  |  |  |  |  |  | |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow| | Z| | | | | | | | }}
{{srow| Z| Z| S|  |  |  | L| O| O| J}}
{{srow| Z| T| S| S| | | L| O| O| J}}
{{srow| T| T| S| S|  |  | L| L| J| J}}
{{srow| T| T| S| S| | | J| J| L| L}}
{{srow| T| T|-T| S| | | J| O| O| L}}
{{srow| T| Z|-T|-T| |  | J| O| O| L}}
{{srow| Z| Z|-T|-T|  |  |-J|-J|-L|-L}}
{{srow| Z|-Z|-T|-T|  | I|-J|-O|-O|-L}}
{{srow|-Z|-Z|-S|-T|  | I|-J|-O|-O|-L}}
{{srow|-Z|-Z|-S|-S|  | I|-J|-J|-L|-L}}
{{srow|-Z|-Z|-S|-S|  | I|-J|-O|-O|-L}}
{{srow|-Z|-T|-S|-S| I|-I|-J|-O|-O|-L}}
{{srow|-T|-T|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S| I|-I|-L|-L|-J|-J}}
{{pfend}}
{{pfend}}
Drop T
|-
|{{pfstart}}
! align=center | bag 9
{{pfrow| | | | | | | | | | }}
| style="padding-left: 8pt; padding-right:6pt;" | Use T and J for Single line skimming. Score a Tetris with I. Put L with its head down on the edge of the LJO stack and place O beside it.
{{pfrow| | |S| | | | | | | }}
| {{sstart}}
{{pfrow| |T|S|S| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|T|T|T|S| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|G|G|G|G| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  | Z|  |  |  |  | L|  |  |  }}
{{srow| Z| Z| S|  |  |  | L|  | O| O}}
{{srow| Z|-Z| S| S|  |  | L| L| O| O}}
{{srow|-Z|-Z|-S| S|  |  |-L|-O|-O|-J}}
{{srow|-Z|-T|-S|-S| | T|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S| T| T|-L|-L|-J|-J}}
{{srow|-T|-T|-S|-S| | T|-J|-J|-L|-L}}
{{srow|-T|-T|-T|-S| | J|-J|-O|-O|-L}}
{{srow|-T|-Z|-T|-T| | J|-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T| J| J|-J|-J|-L|-L}}
{{srow|-Z|-Z|-T|-T| I|-I|-J|-O|-O|-L}}
{{srow|-Z|-Z|-S|-T| I|-I|-J|-O|-O|-L}}
{{srow|-Z|-Z|-S|-S| I|-I|-J|-J|-L|-L}}
{{srow|-Z|-Z|-S|-S| I|-I|-J|-O|-O|-L}}
{{pfend}}
{{pfend}}
[[SRS]] and [[TGM rotation|TGM]]<br>allow this
|-
|{{pfstart}}
! align=center | bag 10
{{pfrow| |Z| | | | | | | | }}
| style="padding-left: 8pt; padding-right:6pt;" | Hold J until the very end of the bag. Use T and J for Single line skimming. Score a Tetris with I. Put L with its head up on top of the other L.
{{pfrow|Z|Z|S| | | | | | | }}
| {{sstart}}
{{pfrow|Z|T|S|S| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|T|T|T|S| | | | | | }}
{{srow|  |  |  | |  |  |  |  |  |  }}
{{pfrow|G|G|G|G| | | | | | }}
{{srow|  |  |  |  |  | |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow| | |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  | Z|  |  |  | J|  |  |  |  }}
{{srow| Z| Z| S|  |  | J| L| L| O| O}}
{{srow| Z|-Z| S| S| J| J|-L| L| O| O}}
{{srow|-Z|-Z|-S| S| | T|-L| L|-O|-O}}
{{srow|-Z|-Z|-S|-S| T| T|-L|-L|-O|-O}}
{{srow|-Z|-Z|-S|-S|  | T|-L|-O|-O|-J}}
{{srow|-Z|-T|-S|-S| I|-T|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S| I|-T|-J|-J|-L|-L}}
{{srow|-T|-T|-T|-S| I|-J|-J|-O|-O|-L}}
{{srow|-T|-Z|-T|-T| I|-J|-J|-O|-O|-L}}
{{pfend}}
{{pfend}}
Drop Z
|}
|}
<br>
=== 20G loop ===
[[Image:Forever-gravity.gif|right|frame|A 70 pieces run of this 20G capable strategy.]]


ZTS: Mirror image of STZ
This is a slight variation of the technique above. It works under 20G gravity, that means a piece is pulled down immediately to the ground. On the other hand, another requirement must be met, namely that it must be possible to drop the first 2 I pieces and the second and third T piece on the stack for the S pieces. Note that most modes with gravity (e.g. Marathon) don't start with 20G, so this requirement is pretty much just formally.


SZT, ZST: hold the first tetromino and play as above
Here the I piece section is on the left side, the S,Z,T section is in the middle and the L,J,O section is on the right side. We also assume that the third I piece is dropped horizontally on the very left. This assumption is not needed, but it simplifies the execution.


=== 1210 ===
{{pfstart}}
{{pfstart}}
{{pfrow| | | | | | | | | | }}
{{pfrow| | | | | | | | | | }}
{{pfrow| |G| | | | | | | | }}
{{pfrow| | | | | | | | | | }}
{{pfrow|G|G|G| | | | | | | }}
{{pfrow| | | | | | | | | | }}
{{pfrow| | | | |S| | | | | }}
{{pfrow| | | | |S|S| | | | }}
{{pfrow| | | | |S|S| | | | }}
{{pfrow| | | | |S|S| | | | }}
{{pfrow| | | | |T|S| | | | }}
{{pfrow| | | | |T|T| | | | }}
{{pfrow|I|I|I|I|T|I|J|J|L|L}}
{{pfrow| | | |Z|I|I|J|O|O|L}}
{{pfrow| | |Z|Z|I|I|J|O|O|L}}
{{pfrow| | |Z|Z|I|I|J|J|L|L}}
{{pfrow| | |Z|Z|I|T|J|O|O|L}}
{{pfrow| | |Z|Z|T|T|J|O|O|L}}
{{pfrow| | |Z|Z|S|T|J|J|L|L}}
{{pfrow| | |Z|T|S|S|J|O|O|L}}
{{pfrow| | |T|T|T|S|J|O|O|L}}
{{pfend}}
{{pfend}}
Becomes 0112.


SZT, ZST, STZ:
Newly spawned pieces will always touch the top of the S piece stack. At the end of each bag, the S piece stack is 2 or 6 columns higher than the Z piece stack. So even if a piece shows up in the bag between S and Z, it can still be moved to the left side. Similarly at the end of each bag, the S piece stack is always at least 3 columns higher than the L,J,O section. Thus, pieces can always be moved to the right side.
{{pfstart}}
 
{{pfrow| | | |T| | | | | | }}
{| border=1 cellspacing=0
{{pfrow| |Z|T|T| | | | | | }}
|-
{{pfrow|Z|Z|S|T| | | | | | }}
! width=80 align=center | bags 1 & 2
{{pfrow|Z|G|S|S| | | | | | }}
| width=200 style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on Z stack. Score a Tetris with second I.
{{pfrow|G|G|G|S| | | | | | }}
| {{sstart}}
{{srow|  |  |  |  | S|  |  |  |  |  }}
{{srow|  |  |  |  | S| S|  |  |  |  }}
{{srow|  |  |  | Z| S| S|  |  |  |  }}
{{srow|  |  | Z| Z| S| S|  |  |  |  }}
{{srow|  |  | Z| T|-S| S| J| J| L| L}}
{{srow|  |  | T| T|-S|-S| J| O| O| L}}
{{srow|  |  | T| T|-S|-S| J| O| O| L}}
{{srow| | | T| T|-S|-S| J| J| L| L}}
{{srow| |  | T| Z|-T|-S| J| O| O| L}}
{{srow|  |  | Z| Z|-T|-T| J| O| O| L}}
{{srow|  |  | Z|-Z|-I|-I|-J|-O|-O|-L}}
{{srow| |  |-Z|-Z|-I|-I|-J|-O|-O|-L}}
{{srow|  |  |-Z|-Z|-I|-I|-J|-J|-L|-L}}
{{srow|  |  |-Z|-Z|-I|-T|-J|-O|-O|-L}}
{{srow| I| I|-Z|-Z|-T|-T|-J|-O|-O|-L}}
{{srow| I| I|-Z|-Z|-S|-T|-J|-J|-L|-L}}
{{srow| I| I|-Z|-T|-S|-S|-J|-O|-O|-L}}
{{srow| I| I|-T|-T|-T|-S|-J|-O|-O|-L}}
{{pfend}}
{{pfend}}
ZTS, TSZ, TZS: hold the T and play as above
|-
 
! align=center | bag 3
=== 0112 ===
| style="padding-left: 8pt; padding-right:6pt;" | Use T and J for Single line skimming. Hold I until the end of the bag and then score a Tetris. Put L with its head down on the edge of the LJO stack and place O beside it.
{{pfstart}}
| {{sstart}}
{{pfrow| | | | | | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | |G| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| |G|G|G| | | | | | }}
{{srow|  |  |  |  | S|  |  |  |  |  }}
{{srow|  |  |  |  | S| S|  |  |  |  }}
{{srow|  |  |  | Z|-S| S|  |  |  |  }}
{{srow|  |  | Z| Z|-S|-S| L|  |  |  }}
{{srow|  |  | Z|-Z|-S|-S| L|  | O| O}}
{{srow|  |  |-Z|-Z|-S|-S| L| L| O| O}}
{{srow|  |  |-Z|-T|-S|-S|-J|-J|-L|-L}}
{{srow|  |  |-T|-T|-S|-S|-J|-O|-O|-L}}
{{srow|  |  |-T|-T|-S|-S|-J|-O|-O|-L}}
{{srow|  |  |-T|-T|-S|-S|-J|-J|-L|-L}}
{{srow| I| J|-T|-Z|-T|-S|-J|-O|-O|-L}}
{{srow| I| J|-Z|-Z|-T|-T|-J|-O|-O|-L}}
{{srow| J| J|-Z|-Z|-I|-I|-J|-O|-O|-L}}
{{srow| I| T|-Z|-Z|-I|-I|-J|-O|-O|-L}}
{{srow| T| T|-Z|-Z|-I|-I|-J|-J|-L|-L}}
{{srow| I| T|-Z|-Z|-I|-T|-J|-O|-O|-L}}
{{pfend}}
{{pfend}}
Becomes 2101.
|-
 
! align=center | bag 4
TSZ, TZS, ZTS:
| style="padding-left: 8pt; padding-right:6pt;" | Use T and J for Single line skimming. Hold I until the end of the bag and then score a Tetris. Put L with its head up on top of the other L and place O beside it.
{{pfstart}}
| {{sstart}}
{{pfrow|S| | | | | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|S|S| |Z| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|T|S|Z|Z| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|T|T|Z|G| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|T|G|G|G| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  | S|  |  |  |  |  }}
{{srow|  |  |  |  | S| S|  |  |  |  }}
{{srow|  |  | | Z|-S| S| | | | }}
{{srow| | | Z| Z|-S|-S|  |  |  |  }}
{{srow|  |  | Z|-Z|-S|-S| L| L| O| O}}
{{srow|  |  |-Z|-Z|-S|-S|-L| L| O| O}}
{{srow| I| T|-Z|-Z|-S|-S|-L| L|-O|-O}}
{{srow| T| T|-Z|-Z|-S|-S|-L|-L|-O|-O}}
{{srow| I| T|-Z|-T|-S|-S|-J|-J|-L|-L}}
{{srow| I| J|-T|-T|-S|-S|-J|-O|-O|-L}}
{{srow| I| J|-T|-T|-S|-S|-J|-O|-O|-L}}
{{srow| J| J|-T|-T|-S|-S|-J|-J|-L|-L}}
{{pfend}}
{{pfend}}
ZST, STZ, SZT: hold the S and play as above
|-
 
! align=center | bags 5 & 6
=== 2101 ===
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Score a Tetris with second I.
{{pfstart}}
| {{sstart}}
{{pfrow| | | | | | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|G| | | | | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|G|G| |G| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  | T|  |  |  |  |  }}
{{srow|  |  |  |  | T| T|  |  |  |  }}
{{srow|  |  |  |  | T| T|  |  |  |  }}
{{srow|  |  |  |  | T| T|  |  |  |  }}
{{srow|  |  |  |  | S| T|  |  |  |  }}
{{srow|  |  |  |  | S| S|  |  |  |  }}
{{srow|  |  |  | Z| S| S| J| J| L| L}}
{{srow|  |  | Z| Z| S| S| J| O| O| L}}
{{srow|  |  | Z| Z|-S| S| J| O| O| L}}
{{srow|  |  | Z| Z|-S|-S| J| J| L| L}}
{{srow| I| I| Z|-Z|-S|-S| J| O| O| L}}
{{srow| I| I|-Z|-Z|-S|-S| J| O| O| L}}
{{srow| I| I|-Z|-Z|-S|-S|-L|-L|-O|-O}}
{{srow| I| I|-Z|-Z|-S|-S|-L|-L|-O|-O}}
{{pfend}}
{{pfend}}
Becomes 1021 or flat.
|-
 
! align=center | bags 7 & 8
ZST, ZTS, SZT:
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on Z stack. Score a Tetris with second I.
{|
| {{sstart}}
|{{pfstart}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | |T| | | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|S| |T|T| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|S|S|T|Z| | | | | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow|G|S|Z|Z| | | | | | }}
{{srow|  |  |  |  | S| |  |  |  |  }}
{{pfrow|G|G|Z|G| | | | | | }}
{{srow| |  |  |  | S| S|  |  |  |  }}
{{srow|  |  |  | T| S| S|  |  |  |  }}
{{srow| | | T| T| S| S| | | | }}
{{srow|  |  | T| T|-T| S| L| O| O| J}}
{{srow|  |  | T| T|-T|-T| L| O| O| J}}
{{srow|  |  | T| Z|-T|-T| L| L| J| J}}
{{srow|  |  | Z| Z|-T|-T| J| J| L| L}}
{{srow|  |  | Z| Z|-S|-T| J| O| O| L}}
{{srow|  |  | Z| Z|-S|-S| J| O| O| L}}
{{srow| I| I| Z|-Z|-S|-S|-J|-J|-L|-L}}
{{srow| I| I|-Z|-Z|-S|-S|-J|-O|-O|-L}}
{{srow| I| I|-Z|-Z|-S|-S|-J|-O|-O|-L}}
{{srow| I| I|-Z|-Z|-S|-S|-J|-J|-L|-L}}
{{pfend}}
{{pfend}}
To 1021
|-
|{{pfstart}}
! align=center | bags 9 & 10
{{pfrow| | | | | | | | | | }}
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on Z stack. Score a Tetris with second I.
{{pfrow|S|T|T|T| | | | | | }}
| {{sstart}}
{{pfrow|S|S|T|Z| | | | | | }}
{{srow|  |  |  |  | T|  |  |  |  |  }}
{{pfrow|G|S|Z|Z| | | | | | }}
{{srow|  |  |  |  | T| T|  |  |  |  }}
{{pfrow|G|G|Z|G| | | | | | }}
{{srow|  |  |  |  | T| T|  |  |  |  }}
{{srow|  |  |  |  | T| T|  |  |  |  }}
{{srow|  |  |  |  | S| T|  |  |  |  }}
{{srow|  |  |  |  | S| S|  |  |  |  }}
{{srow|  |  |  | Z| S| S| J| J| L| L}}
{{srow|  |  | Z| Z| S| S| J| O| O| L}}
{{srow| | | Z| Z|-S| S| J| O| O| L}}
{{srow|  |  | Z| Z|-S|-S| L| O| O| J}}
{{srow|  |  | Z|-T|-S|-S| L| O| O| J}}
{{srow|  |  |-T|-T|-S|-S| L| L| J| J}}
{{srow|  | |-T|-T|-T|-S|-L|-O|-O|-J}}
{{srow|  |  |-T|-T|-T|-T|-L|-O|-O|-J}}
{{srow| I| I|-T|-Z|-T|-T|-L|-L|-J|-J}}
{{srow| I| I|-Z|-Z|-T|-T|-J|-J|-L|-L}}
{{srow| I| I|-Z|-Z|-S|-T|-J|-O|-O|-L}}
{{srow| I| I|-Z|-Z|-S|-S|-J|-O|-O|-L}}
{{pfend}}
{{pfend}}
To flat
|}
|}
TSZ, TZS, STZ: hold the T and play as above
<br>
 
=== No previews loop ===
 
[[Image:Forever-previewless.gif|right|frame|A 70 pieces run without usage of next piece queue.]]
 
This is another slight variation of the technique above. It works with 0 previews, that means the player doesn't need any knowledge of the next piece queue. On the other hand, another requirement must be met, namely that it must be possible to drop the first 2 I pieces horizontally on the L,J,O section. If this isn't fulfilled, then you may have to restart. Here the S,Z,T section is on the left side, the L,J,O section is in the middle and the I piece section is on the right side.


=== 1021 ===
{{pfstart}}
{{pfstart}}
{{pfrow| | | | | | | | | | }}
{{pfrow| | | | | | | | | | }}
{{pfrow| | |G| | | | | | | }}
{{pfrow| | | | | | | | | | }}
{{pfrow|G| |G|G| | | | | | }}
{{pfrow| | | | | | | | | | }}
{{pfend}}
{{pfrow| | | | | | | | | | }}
Becomes 1210.
{{pfrow| | | | | | | | | | }}
 
{{pfrow| | | | | | | | | | }}
TSZ, TZS, ZTS:
{{pfrow| | | | | | | | | | }}
{{pfstart}}
{{pfrow| | | | | | | | | | }}
{{pfrow| |Z| | | | | | | | }}
{{pfrow| |T| | | | | | | | }}
{{pfrow|Z|Z|S| | | | | | | }}
{{pfrow|T|T| | |L|O|O|J| | }}
{{pfrow|Z|T|S|S| | | | | | }}
{{pfrow|T|T| | |L|O|O|J| | }}
{{pfrow|T|T|G|S| | | | | | }}
{{pfrow|T|T| | |L|L|J|J| | }}
{{pfrow|G|T|G|G| | | | | | }}
{{pfrow|T|Z| | |I|I|I|I| | }}
{{pfrow|Z|Z|S| |J|J|L|L| | }}
{{pfrow|Z|Z|S|S|J|O|O|L| | }}
{{pfrow|Z|Z|S|S|J|O|O|L| | }}
{{pfrow|Z|Z|S|S|L|O|O|J|I| }}
{{pfrow|Z|Z|S|S|L|O|O|J|I| }}
{{pfrow|Z|T|S|S|L|L|J|J|I| }}
{{pfrow|T|T|T|S|I|I|I|I|I| }}
{{pfend}}
{{pfend}}
ZST, STZ, SZT: hold the Z and play as above
=== 0121 ===
Becomes 2110 through a mirror of the plays used for 1210.
=== 2110 ===
Becomes 1012 through a mirror of the plays used for 0112.


=== 1012 ===
If L resp. J shows up before O in the bag, then it is dropped with its head down. In contrast to the standard technique, sonic drop is used for J or L pieces instead of O pieces. More precisely, sonic drop is needed, if the piece order is L-O-J or J-O-L within a bag. The column to the left and to the right of the L,J,O section must be empty above the L,J,O stack. This is also why the L,J,O section must be in the middle.
Becomes 1201 through a mirror of the plays used for 2101.


=== 1201 ===
T pieces are dropped first on the Z piece stack. At the end of each bag, the Z piece stack is higher than the S piece stack. Together with the 2 horizontal dropped I pieces, it guarantees that the L,J,O stack is at least 2 columns higher than the S piece stack. Thus, it is always possible to move a L piece under an O piece (in case of the piece order J-O-L).
Becomes 0121 through a mirror of the plays used for 1021.


== L, J, and O tetrominoes ==
{| border=1 cellspacing=0
Well starts and ends flat.
|-
 
! width=80 align=center | bags 1 & 2
LJO, JLO:
| width=200 style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Score a Tetris with first I.
{{pfstart}}
| {{sstart}}
{{pfrow| | | | | | |L|O|O|J}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | |L|O|O|J}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | |L|L|J|J}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  | J| J| L| L|  |  }}
{{srow|  | Z|  |  | J| O| O| L|  |  }}
{{srow| Z| Z| S|  | J| O| O| L|  |  }}
{{srow| Z| Z| S| S| L| O| O| J|  |  }}
{{srow| Z| Z| T| S| L| O| O| J|  |  }}
{{srow| Z|-T| T| T| L| L| J| J|  |  }}
{{srow|-T|-T| T| T|-L|-O|-O|-J|  |  }}
{{srow|-T|-T| T| T|-L|-O|-O|-J|  |  }}
{{srow|-T|-T| S| T|-L|-L|-J|-J|  |  }}
{{srow|-T|-Z| S| S|-I|-I|-I|-I| I|  }}
{{srow|-Z|-Z|-S| S|-J|-J|-L|-L| I|  }}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L| I|  }}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L| I|  }}
{{srow|-Z|-Z|-S|-S|-L|-O|-O|-J|-I| I}}
{{srow|-Z|-Z|-S|-S|-L|-O|-O|-J|-I| I}}
{{srow|-Z|-T|-S|-S|-L|-L|-J|-J|-I| I}}
{{srow|-T|-T|-T|-S|-I|-I|-I|-I|-I| I}}
{{pfend}}
{{pfend}}
OLJ, OJL:
|-
{{pfstart}}
! align=center | bags 3 & 4
{{pfrow| | | | | | |J|J|L|L}}
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on Z stack. Score a Tetris with first I.
{{pfrow| | | | | | |J|O|O|L}}
| {{sstart}}
{{pfrow| | | | | | |J|O|O|L}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  | Z|  |  |  |  |  |  |  |  }}
{{srow| Z| Z|  |  | J| J| L| L|  |  }}
{{srow| Z| T|  |  | J| O| O| L|  |  }}
{{srow| T| T|  |  | J| O| O| L|  |  }}
{{srow| T| T|  |  | L| O| O| J|  |  }}
{{srow| T| T| S|  | L| O| O| J|  |  }}
{{srow| T| Z| S| S| L| L| J| J|  |  }}
{{srow| Z| Z| S| S|-J|-J|-L|-L|  |  }}
{{srow| Z|-Z| S| S|-J|-O|-O|-L|  |  }}
{{srow|-Z|-Z|-S| S|-J|-O|-O|-L| |  }}
{{srow|-Z|-Z|-S|-S|-L|-O|-O|-J| |  }}
{{srow|-Z|-Z|-T|-S|-L|-O|-O|-J| |  }}
{{srow|-Z|-T|-T|-T|-L|-L|-J|-J| I|  }}
{{srow|-T|-T|-T|-T|-L|-O|-O|-J| I|  }}
{{srow|-T|-T|-T|-T|-L|-O|-O|-J| I|  }}
{{srow|-T|-T|-S|-T|-L|-L|-J|-J| I|  }}
{{srow|-T|-Z|-S|-S|-I|-I|-I|-I|-I| I}}
{{srow|-Z|-Z|-S|-S|-J|-J|-L|-L|-I| I}}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L|-I| I}}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L|-I| I}}
{{pfend}}
{{pfend}}
JOL:
|-
{|
! align=center | bags 5 & 6
|{{pfstart}}
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Score a Tetris with first I.
{{pfrow| | | | | | |J|J| | }}
| {{sstart}}
{{pfrow| | | | | | |J| | | }}
{{srow|  |  |  |  | J| J| L| L|  |  }}
{{pfrow| | | | | | |J| | | }}
{{srow|  | Z|  |  | J| O| O| L|  |  }}
{{srow| Z| Z| T|  | J| O| O| L|  |  }}
{{srow| Z| Z| T| T| L| O| O| J|  |  }}
{{srow| Z| Z| T| T| L| O| O| J|  |  }}
{{srow| Z|-Z| T| T| L| L| J| J|  |  }}
{{srow|-Z|-Z| S| T|-J|-J|-L|-L|  |  }}
{{srow|-Z|-T| S| S|-J|-O|-O|-L|  |  }}
{{srow|-T|-T| S| S|-J|-O|-O|-L|  |  }}
{{srow|-T|-T| S| S|-L|-O|-O|-J| |  }}
{{srow|-T|-T|-S| S|-L|-O|-O|-J|  |  }}
{{srow|-T|-Z|-S|-S|-L|-L|-J|-J|  |  }}
{{srow|-Z|-Z|-S|-S|-J|-J|-L|-L|  |  }}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L| I|  }}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L| I|  }}
{{srow|-Z|-Z|-S|-S|-L|-O|-O|-J| I|  }}
{{srow|-Z|-Z|-T|-S|-L|-O|-O|-J| I| }}
{{srow|-Z|-T|-T|-T|-L|-L|-J|-J|-I| I}}
{{srow|-T|-T|-T|-T|-L|-O|-O|-J|-I| I}}
{{srow|-T|-T|-T|-T|-L|-O|-O|-J|-I| I}}
{{srow|-T|-T|-S|-T|-L|-L|-J|-J|-I| I}}
{{pfend}}
{{pfend}}
Drop J
|-
|{{pfstart}}
! align=center | bag 7
{{pfrow| | | | | | |J|J| | }}
| style="padding-left: 8pt; padding-right:6pt;" |  Use T and L for Single line skimming. Score a Tetris with I. Put J with its head down on the edge of the LJO stack and place O beside it.
{{pfrow| | | | | | |J| |O|O}}
| {{sstart}}
{{pfrow| | | | | | |J| |O|O}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  | J|  |  }}
{{srow|  |  |  |  | O| O|  | J|  |  }}
{{srow|  | Z|  |  | O| O| J| J|  |  }}
{{srow| Z| Z| S|  |-J|-J|-L|-L| | }}
{{srow| Z|-Z| S| S|-J|-O|-O|-L|  |  }}
{{srow|-Z|-Z|-T| S|-J|-O|-O|-L|  |  }}
{{srow|-Z|-Z|-T|-T|-L|-O|-O|-J| |  }}
{{srow|-Z|-Z|-T|-T|-L|-O|-O|-J|  |  }}
{{srow|-Z|-Z|-T|-T|-L|-L|-J|-J| |  }}
{{srow|-Z|-Z|-S|-T|-J|-J|-L|-L|  |  }}
{{srow|-Z|-T|-S|-S|-J|-O|-O|-L| T|  }}
{{srow|-T|-T|-S|-S|-J|-O|-O|-L| T| T}}
{{srow|-T|-T|-S|-S|-L|-O|-O|-J| T|  }}
{{srow|-T|-T|-S|-S|-L|-O|-O|-J| L|  }}
{{srow|-T|-Z|-S|-S|-L|-L|-J|-J| L|  }}
{{srow|-Z|-Z|-S|-S|-J|-J|-L|-L| L| L}}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L|-I| I}}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L|-I| I}}
{{srow|-Z|-Z|-S|-S|-L|-O|-O|-J|-I| I}}
{{srow|-Z|-Z|-T|-S|-L|-O|-O|-J|-I| I}}
{{pfend}}
{{pfend}}
Soft-drop O
|-
|{{pfstart}}
! align=center | bag 8
{{pfrow| | | | | | |J|J| | }}
| style="padding-left: 8pt; padding-right:6pt;" | Use T and L for Single line skimming. Score a Tetris with I. Put J with its head up on top of the other J and place O beside it.
{{pfrow| | | | | | |J|O|O| }}
| {{sstart}}
{{pfrow| | | | | | |J|O|O| }}
{{srow| | | | | | |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  | O| O| J| J| | }}
{{srow| | Z| | | O| O| J|-J|  |  }}
{{srow| Z| Z| S|  |-O|-O| J|-J|  |  }}
{{srow| Z|-Z| S| S|-O|-O|-J|-J|  |  }}
{{srow|-Z|-Z|-S| S|-J|-J|-L|-L|  |  }}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L| L|  }}
{{srow|-Z|-Z|-T|-S|-J|-O|-O|-L| L|  }}
{{srow|-Z|-Z|-T|-T|-L|-O|-O|-J| L| L}}
{{srow|-Z|-Z|-T|-T|-L|-O|-O|-J| T|  }}
{{srow|-Z|-Z|-T|-T|-L|-L|-J|-J| T| T}}
{{srow|-Z|-Z|-S|-T|-J|-J|-L|-L| T|  }}
{{srow|-Z|-T|-S|-S|-J|-O|-O|-L|-T| I}}
{{srow|-T|-T|-S|-S|-L|-O|-O|-J|-T| I}}
{{srow|-T|-T|-S|-S|-L|-O|-O|-J|-L| I}}
{{srow|-T|-Z|-S|-S|-L|-L|-J|-J|-L| I}}
{{pfend}}
{{pfend}}
Slide O
|-
|{{pfstart}}
! align=center | bags 9 & 10
{{pfrow| | | | | | |J|J|L|L}}
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on Z stack. Score a Tetris with first I.
{{pfrow| | | | | | |J|O|O|L}}
| {{sstart}}
{{pfrow| | | | | | |J|O|O|L}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  | Z|  |  |  |  |  |  |  |  }}
{{srow| Z| Z|  |  | J| J| L| L|  |  }}
{{srow| Z| T|  |  | J| O| O| L|  |  }}
{{srow| T| T|  |  | J| O| O| L|  |  }}
{{srow| T| T|  |  | L| O| O| J|  |  }}
{{srow| T| T| S| | L| O| O| J| |  }}
{{srow| T| Z| S| S| L| L| J| J|  |  }}
{{srow| Z| Z| S| S|-O|-O|-J|-J|  |  }}
{{srow| Z|-Z| S| S|-O|-O|-J|-J| I|  }}
{{srow|-Z|-Z|-S| S|-O|-O|-J|-J| I|  }}
{{srow|-Z|-Z|-S|-S|-O|-O|-J|-J| I|  }}
{{srow|-Z|-Z|-S|-S|-J|-J|-L|-L| I|  }}
{{srow|-Z|-Z|-S|-S|-J|-O|-O|-L|-L| I}}
{{srow|-Z|-Z|-T|-S|-J|-O|-O|-L|-L| I}}
{{srow|-Z|-Z|-T|-T|-L|-O|-O|-J|-T| I}}
{{srow|-Z|-Z|-S|-T|-J|-J|-L|-L|-T| I}}
{{pfend}}
{{pfend}}
Drop L
|}
|}
<br>


LOJ: mirror image of JOL
=== 40 Lines Sprint ===


When playing for speed, it's possible to avoid the soft drop by placing two J, L, or O tetrominoes in the center as described below.
[[Image:Forever-sprint.gif|right|frame|A 102 pieces run of this sprint strategy.]]


== I tetromino ==
This is yet another slight variation of the technique above. Here, the goal is not to loop but rather to clear 40 lines with a minimum number of guaranteed pieces. With this variation 40 lines can always be cleared within 15 bags, that means 104 dropped pieces at maximum and 1 piece in hold.
The player puts I tetrominoes in the center columns and reaps tetrises.


After each 2 rounds of STZ and LJO, the STZ heap has grown by 6 rows, and the LJO heap has grown by 6 rowsHowever, the center has grown only by 4 rows.
{| border=1 cellspacing=0
 
|-
If the STZ heap becomes too high, and its floor is shaped as 1210, 0121, 2101, or 1012, the player can borrow a T tetromino from the STZ heap, place it end-up in columns 5 and 6, and clear a single lineThis results in no change to the floor shape, and it works especially in cases where the player would otherwise have to "hold the T and play as above".
! width=80 align=center | bag 1
 
| width=200 style="padding-left: 8pt; padding-right:6pt;" | Hold Z if it comes before T. Put T horizontal on left side of SZT stack. Spin T if S is already there.
(Illustration coming)
| {{sstart}}
 
{{srow|  |  |  |  |  |  |  |  |  |  }}
If the LJO heap becomes too high, the player can borrow two J tetrominoes to clear single lines in columns 5 and 6 in the same manner as the Ts.
{{srow|  |  |  |  |  |  |  |  |  |  }}
 
{{srow|  |  |  |  |  |  |  |  |  |  }}
(Illustration coming)
{{srow|  |  |  |  |  |  |  |  |  |  }}
 
{{srow|  |  |  |  |  |  |  |  |  |  }}
Then the next L and O tetrominoes form a combo square:
{{srow|  |  |  |  |  |  |  |  |  |  }}
{|
{{srow|  |  |  |  |  |  |  |  |  |  }}
|{{pfstart}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | |L|L| | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | | |L|O|O}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | | |L|O|O}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | |L| | | }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | |L| |O|O}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | |L|L|O|O}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  | Z|  |  |  | I|  |  |  |  }}
{{srow| Z| Z| S|  |  | I| J| J| L| L}}
{{srow| Z| T| S| S|  | I| J| O| O| L}}
{{srow| T| T| T| S|  | I| J| O| O| L}}
{{pfend}}
|-
! align=center | bags 2 & 3
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Put first I on top of existing I and use second I to score a Tetris.
| {{sstart}}
{{srow|  | |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  | S|  |  |  |  |  |  |  }}
{{srow|  |  | S| S|  |  |  |  |  |  }}
{{srow|  |  | T| S|  |  | J| J| L| L}}
{{srow|  | Z| T| T|  | I| J| O| O| L}}
{{srow| Z| Z| T| T|  | I| J| O| O| L}}
{{srow| Z| Z| T| T|  | I| J| J| L| L}}
{{srow| Z| Z| S| T|  | I| J| O| O| L}}
{{srow| Z|-Z| S| S| I|-I| J| O| O| L}}
{{srow|-Z|-Z|-S| S| I|-I|-J|-J|-L|-L}}
{{srow|-Z|-T|-S|-S| I|-I|-J|-O|-O|-L}}
{{srow|-T|-T|-T|-S| I|-I|-J|-O|-O|-L}}
{{pfend}}
|-
! align=center | bags 4 & 5
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on Z stack. Put first I on top of existing I and use second I to score a Tetris.
| {{sstart}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  | T|  |  |  |  |  |  |  |  }}
{{srow| T| T| S|  |  |  | L| O| O| J}}
{{srow| T| T| S| S|  |  | L| O| O| J}}
{{srow| T| T| S| S|  |  | L| L| J| J}}
{{srow| T| Z| S| S|  | I| L| O| O| J}}
{{srow| Z| Z|-S| S|  | I| L| O| O| J}}
{{srow| Z| Z|-S|-S|  | I| L| L| J| J}}
{{srow| Z| Z|-T|-S|  | I|-J|-J|-L|-L}}
{{srow| Z|-Z|-T|-T| I|-I|-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T| I|-I|-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T| I|-I|-J|-J|-L|-L}}
{{srow|-Z|-Z|-S|-T| I|-I|-J|-O|-O|-L}}
{{pfend}}
|-
! align=center | bags 6 & 7
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Score a Tetris with first I.
| {{sstart}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  | S|  |  |  |  |  |  |  }}
{{srow|  |  | S| S|  |  |  |  |  |  }}
{{srow|  |  | T| S|  |  | L| O| O| J}}
{{srow|  | Z| T| T|  |  | L| O| O| J}}
{{srow| Z| Z| T| T|  |  | L| L| J| J}}
{{srow| Z| Z| T| T|  |  | J| J| L| L}}
{{srow| Z| Z| S| T|  |  | J| O| O| L}}
{{srow| Z|-T| S| S|  | I| J| O| O| L}}
{{srow|-T|-T|-S| S|  | I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S|  | I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S|  | I|-L|-L|-J|-J}}
{{srow|-T|-Z|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-S| I|-I|-L|-L|-J|-J}}
{{srow|-Z|-Z|-T|-S| I|-I|-J|-J|-L|-L}}
{{pfend}}
|-
! align=center | bags 8 & 9
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on Z stack. Score a Tetris with first I.
| {{sstart}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow| |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  | T|  |  |  |  |  |  |  |  }}
{{srow| T| T| S|  |  |  | L| O| O| J}}
{{srow| T| T| S| S|  |  | L| O| O| J}}
{{srow| T| T| S| S|  |  | L| L| J| J}}
{{srow| T| Z| S| S|  |  | L| O| O| J}}
{{srow| Z| Z|-S| S|  |  | L| O| O| J}}
{{srow| Z| Z|-S|-S|  |  | L| L| J| J}}
{{srow| Z| Z|-T|-S|  |  |-L|-O|-O|-J}}
{{srow| Z|-Z|-T|-T|  | I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-T|-T|  | I|-L|-L|-J|-J}}
{{srow|-Z|-Z|-T|-T|  | I|-J|-J|-L|-L}}
{{srow|-Z|-Z|-S|-T|  | I|-J|-O|-O|-L}}
{{srow|-Z|-T|-S|-S| I|-I|-J|-O|-O|-L}}
{{srow|-T|-T|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S| I|-I|-L|-L|-J|-J}}
{{pfend}}
|-
! align=center | bags 10 & 11
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on S stack. Score a Tetris with first I.
| {{sstart}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{srow|  |  | S|  |  |  |  |  |  |  }}
{{srow|  |  | S| S|  |  |  |  |  |  }}
{{srow|  |  | T| S|  |  | J| J| L| L}}
{{srow|  | Z| T| T|  |  | J| O| O| L}}
{{srow| Z| Z| T| T|  |  | J| O| O| L}}
{{srow| Z| Z| T| T|  |  | L| O| O| J}}
{{srow| Z| Z| S| T|  |  | L| O| O| J}}
{{srow| Z|-T| S| S|  |  | L| L| J| J}}
{{srow|-T|-T|-S| S|  |  |-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S|  |  |-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S|  |  |-L|-L|-J|-J}}
{{srow|-T|-Z|-S|-S|  | I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-S|  | I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-S|  | I|-L|-L|-J|-J}}
{{srow|-Z|-Z|-T|-S|  | I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-T|-T| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-T|-T| I|-I|-L|-L|-J|-J}}
{{srow|-Z|-Z|-T|-T| I|-I|-J|-J|-L|-L}}
{{srow|-Z|-Z|-S|-T| I|-I|-J|-O|-O|-L}}
{{pfend}}
|-
! align=center | bags 12 & 13
| style="padding-left: 8pt; padding-right:6pt;" | Hold first T until second T shows up and drop them both on Z stack. Score a Tetris with first I. Score a Double with second O. Put L and J with their heads down.
| {{sstart}}
{{srow|  | T|  |  |  |  |  |  |  |  }}
{{srow| T| T| S|  |  |  | L|  |  | J}}
{{srow| T| T| S| S|  |  | L|  |  | J}}
{{srow| T| T| S| S|  |  | L| L| J| J}}
{{srow| T| Z| S| S|  |  | J| J| L| L}}
{{srow| Z| Z|-S| S|  |  | J| O| O| L}}
{{srow| Z| Z|-S|-S|  |  | J| O| O| L}}
{{srow| Z| Z|-T|-S|  |  |-J|-J|-L|-L}}
{{srow| Z|-Z|-T|-T|  |  |-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T|  |  |-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T| | I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-T|  | I|-L|-O|-O|-J}}
{{srow|-Z|-T|-S|-S| | I|-L|-L|-J|-J}}
{{srow|-T|-T|-S|-S| | I|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S| O| O|-L|-O|-O|-J}}
{{srow|-T|-T|-S|-S| O| O|-L|-L|-J|-J}}
{{srow|-T|-Z|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-S| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-S| I|-I|-L|-L|-J|-J}}
{{srow|-Z|-Z|-T|-S| I|-I|-L|-O|-O|-J}}
{{pfend}}
{{pfend}}
|{{pfstart}}
|-
{{pfrow| | | | | | | | | | }}
! align=center | bags 14 & 15
{{pfrow| | | | | | | | | | }}
| style="padding-left: 8pt; padding-right:6pt;" | Use both T pieces for Single line skimming. Use both O pieces for scoring Doubles. Score a Tetris with first I. Put second I on hold until second T shows up, then score a Tetris.
{{pfrow| | | | | | |L|L|O|O}}
| {{sstart}}
{{pfrow| | | | | | |L|L|O|O}}
{{srow|  |  |  |  |  |  |  |  |  |  }}
{{pfrow| | | | | | |L|L|O|O}}
{{srow| | | | | | | | | | }}
{{pfrow| | | | | | |L|L|O|O}}
{{srow| | Z| | | | | | | | }}
{{srow| Z| Z| S| | | | L|  |  | J}}
{{srow| Z| Z| S| S|  |  | L|  |  | J}}
{{srow| Z| Z| S| S|  |  | L| L| J| J}}
{{srow| Z|-T| S| S| O| O| L| L| J| J}}
{{srow|-T|-T|-S| S| O| O|-L| L| J|-J}}
{{srow|-T|-T|-S|-S| I| T|-L| L| J|-J}}
{{srow|-T|-T|-S|-S| T| T|-L|-L|-J|-J}}
{{srow|-T|-Z|-S|-S| I| T|-J|-J|-L|-L}}
{{srow|-Z|-Z|-S|-S| I| T|-J|-O|-O|-L}}
{{srow|-Z|-Z|-S|-S| T| T|-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-S| I| T|-J|-J|-L|-L}}
{{srow|-Z|-Z|-T|-T| O| O|-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T| O| O|-J|-O|-O|-L}}
{{srow|-Z|-Z|-T|-T| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-Z|-S|-T| I|-I|-L|-O|-O|-J}}
{{srow|-Z|-T|-S|-S| I|-I|-L|-L|-J|-J}}
{{srow|-T|-T|-S|-S| I|-I|-L|-O|-O|-J}}
{{pfend}}
{{pfend}}
|}
|}
 
-->
== Open questions ==
Adapting this method to the following situations is left as an exercise for the reader:
*High [[Drop#Gravity|gravity]]
*No [[hold piece]]
*[[Garbage]]
*14-piece bag randomizer
*[[TGM randomizer]]


== See also ==
== See also ==
*[[ST stacking]], a method of making back-to-back T-spin doubles
*[[ST stacking]], a method of making back-to-back T-spin doubles
==External links==
*[http://citeseer.ist.psu.edu/34848.html How to Lose at Tetris]
*[http://arxiv.org/abs/cs.CC/0210020 Tetris is Hard, Even to Approximate]
*[http://en.wikipedia.org/wiki/Tetromino#Tiling_the_rectangle_and_filling_the_box_with_2D_pieces Tiling a rectangular space with tetrominoes]
*[http://harddrop.com/forums/index.php?showtopic=7096&st=0&p=83947&#entry83947 A Shorter Loop for Playing Forever]
[[Category:Guides]]

Latest revision as of 13:10, 27 January 2020

A 140-tetromino run of this strategy.

The following outlines a method of playing forever given the following conditions, which apply in many Tetris products since 2001:

Standard procedure

The 10x56 cell tiling that this method creates

The general method is achieved by dividing the screen into self contained sections as shown below. Specifically, the 4 left columns, the 4 right columns, and the 2 middle columns will be treated as distinct regions, with specific pieces assigned exclusively to each region. Because the random generator provides strings of bags containing each of the 7 pieces in a random order, it is possible to construct a strategy around the relatively small variation, with looping patterns.

S, T, and Z will be placed to the left, L, J, and O will be placed to the right, and I pieces will fill the middle.

 Z   I
ZZS  ILOOJ
ZTSS ILOOJ
TTTS ILLJJ


The S, T, and Z piece loop

STTT
SSTZ
SSZZ
SSZZ
TSZZ
TTZT
TZTT
ZZST
ZZSS
ZZSS
ZTSS
TTTS

This pattern loops after 4 bags of pieces. Depending on the order of the pieces for each bag, you may need to use Hold to force a piece to come last. Piece previews are technically not required to play this pattern.


The Z piece must drop after T, so use Hold to change the order if necessary:

 Z
ZZS
ZTSS
TTTS
GGGG


The T piece must not drop first, so use Hold to change the order if necessary:

   T
 ZTT
ZZST
ZGSS
GGGS

Option 1

T
TT
TZ
ZZS
ZGSS
GGGS

Option 2

The T piece must land diagonally adjacent to the other T, so use Hold to change the order if necessary:

S
SS Z
TSZZ
TTZG
TGGG
GGGG

Option 1 (needs
T before S)

S
SS Z
GSZZ
GGZT
GGTT
GGGT

Option 2 (needs
T before Z)

The T piece must drop last, so use Hold to change the order if necessary:

STTT
SSTZ
GSZZ
GGZG


The L, J, and O piece loop

This pattern loops after a single bag of pieces. Depending on the order of the pieces, you will need to use a different construction. At least 5 previews are required to choose the appropriate construction. Alternatively, it is possible to use 3 previews and clever use of Hold (that does not conflict with the STZ loop's Hold needs) to choose an approriate construction using some advanced techniques.

O first (OJL, OLJ):

      JJLL
      JOOL
      JOOL

O last (JLO, LJO):

      LOOJ
      LOOJ
      LLJJ

JOL: (mirror for LOJ)

      JJ
      J
      J

Drop J

      JJ
      J OO
      J OO

Soft-drop O

      JJ
      JOO
      JOO

Slide O

      JJLL
      JOOL
      JOOL

Drop L

Advanced techniques for when only 3 previews are available

Worst case bag distributions such as H?XX?X? and H?XXX?? deserve a special mention. The first piece 'H' denotes a piece which must be placed in Hold in order to follow the STZ loop procedure. Pieces from the LJO loop are denoted by '?', and the remaining pieces are denoted by 'X'. Using 3 previews and Hold, it is only possible to see the first 4 pieces of the bag before the second piece enters the screen. This means you only see H?XX, and only know the first piece of the LJO loop. Because H must be put in Hold, you are forced to make a decision without knowing the order of the rest of the LJO loop. If the O comes first, you can follow the procedure above without problems. The rest of the time you will run into complications like this:

Impossible O placement (eg. HLXXJXO, HLXXXJO):

      JJLL
      J  L
      J  L

Impossible J placement (eg. HLXXOXJ, HLXXXOJ):

      LOO
      LOO
      LL


When L or J come first it is impossible to determine which LJO pattern to use without knowing the order of the final 2 pieces. The solution to this problem is to wait until the first L or J piece enters the screen before making a decision. With the held piece, active piece, and 3 previews, you now see 5 pieces into the bag. This allows you to tell the LJO piece order for the case of H?XX?X?. However, in the case of H?XXX?? the order remains unknown. With this final worst case, the STZ loop is guaranteed to be finished before the second and third pieces of the LJO loop are dealt. This means Hold is available! You can start building whichever pattern you prefer, and use Hold to change the order of the final 2 pieces as necessary.

Tricky starts when only 3 previews are available

There is a worst case start that only complicates the very first bag when playing forever. With a sequence such as ?HXX?X? you can see a maximum of 4 pieces into the bag as you place the first piece. It is impossible to Hold the first piece (part of LJO) because the second piece (part of SZT) must be held. Additionally, because the second last piece is also part of the STZ loop, Hold cannot be used to change the order of the the final 2 LJO pieces as discussed above. So a decision must be made with only the first 4 pieces of the bag known. In this case, the solution is to note that the STZ pattern in the previous section requires the Z to be placed last. However, the mirror STZ pattern is equally feasible, and would require the S to be placed last. Because you have these 2 options, it is impossible that the first piece dealt for the STZ loop is required to be placed last. The worst case is now ?SZX?X?, which can be expressed as ?XHX?X?. By holding the first piece, placing the second, and holding the third, you can now see the first 6 pieces of the bag. This then allows you to choose an appropriate LJO pattern.

It should be noted that this affects only the very first bag of playing forever, which is not to be confused with the first bag of every 20-bag loop of playing forever. On subsequent loops, the first piece of the first bag is already in Hold. You can see the first 5 pieces of ?HXX?X? after you put H on Hold, which makes the first piece active, and sums to 5 with the 3 previews. It is only a problem for the first bag of the game because the player is restricted to a maximum of one use of Hold before placing a piece.

The I piece loop

This pattern loops every 2 bags. No use of Hold or piece previews is required. The player must simply alternate putting the I tetromino in columns 5 and 6 to reap tetrises.

    I
    I
    I
    I
    GI
    GI
    GI
    GI

Notice that the alternate JOL method will work only if the first I tetromino of the loop is placed away from the JLO heap.

Balancing the Stacks

Since the loops have a cycle of 4, 1, and 2 bags respectively, after playing 4 bags they will all be flat. However, the I loop will have only placed 8 rows compared to the 12 rows placed by both the STZ and LJO loops.

STTT  LOOJ
SSTZ  LOOJ
SSZZ  LLJJ
SSZZ  JJLL
TSZZIIJOOL
TTZTIIJOOL
TZTTIILOOJ
ZZSTIILOOJ
ZZSSIILLJJ
ZZSSIILOOJ
ZTSSIILOOJ
TTTSIILLJJ

The rows stacked
after 4 bags.

STTT  LOOJ
SSTZ  LOOJ
SSZZ  LLJJ
SSZZ  JJLL
----------
----------
----------
----------
----------
----------
----------
----------

Though of course,
lines have cleared.

STTT  LOOJ
SSTZ  LOOJ
SSZZ  LLJJ
SSZZ  JJLL

Leaving us with a
surplus.

In order to offset this balance, it is necessary to change strategy. Continue to do the standard STZ loop, while using the following LO and IJ loops.

The L, O piece loop

This pattern loops after 2 bags of pieces. Order is not important, and therefore neither Hold nor piece previews are strictly required for it.

        L
      OOL
      OOLL
      OOLL
      OOGL
      GGGL
      GGGG

The I, J piece loop

This pattern loops after 2 bags of pieces. Order is not important, and therefore neither Hold nor piece previews are strictly required for it.

JIIJ:

GGGG  GGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG JGGGG
GGGG JGGGG
GGGGJJGGGG
GGGGJJGGGG
GGGGJGGGGG
GGGGJGGGGG
GGGGIGGGGG
GGGGIGGGGG
GGGGIGGGGG
GGGGIGGGGG
GGGGGGGGGG

Because of line clears, the order is not very important. Even if you place pieces in the opposite order than what is shown, the net change in screen geometry will be the same:

GGGG  GGGG
GGGG JGGGG
GGGG JGGGG
GGGGJJGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG  GGGG
GGGG JGGGG
GGGG JGGGG
----------
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGGJJGGGG
GGGGJJGGGG
GGGGJJGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
----------
----------
----------
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG
GGGG IGGGG

Putting it all together

If you play the standard method for 12 bags, the balancing method for 4 bags, and finally the reverse balancing method (with LO on the left and STZ on the right) for 4 bags, then you will clear the entire screen allowing you to start over again and play indefinitely.

GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG

The net result of
12 bags stacked
the standard way.

STTT
SSTZ
SSZZ
SSZZ
TSZZ  OOLL
TTZT  OOLL
TZTT  OOLL
ZZST  OOLL
ZZSSJJOOLL
ZZSSJIOOLL
ZTSSJIOOLL
TTTSIIOOLL
GGGGIIGGGG
GGGGIJGGGG
GGGGIJGGGG
GGGGJJGGGG
GGGGJJGGGG
GGGGJIGGGG
GGGGJIGGGG
GGGGIIGGGG
GGGGIIGGGG
GGGGIJGGGG
GGGGIJGGGG
GGGGJJGGGG

The rows stacked
after 4 bags of
balanced stacking.

STTT
SSTZ
SSZZ
SSZZ
TSZZ  OOLL
TTZT  OOLL
TZTT  OOLL
ZZST  OOLL
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------

Of course,
line clears
have actually...

STTT
SSTZ
SSZZ
SSZZ
TSZZ  OOLL
TTZT  OOLL
TZTT  OOLL
ZZST  OOLL

...kept things
realistically short.

GGGG
GGGG
GGGG
GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG
GGGG  GGGG

Where we left off.

OOLLJJTTTZ
OOLLJISTZZ
OOLLJISSZZ
OOLLIISSZZ
OOLLIISSZT
OOLLIJTSTT
OOLLIJTTST
OOLLJJTZSS
GGGGJJZZSS
GGGGJIZZSS
GGGGJIZZTS
GGGGIIZTTT
GGGGIIGGGG
GGGGIJGGGG
GGGGIJGGGG
GGGGJJGGGG

4 bags balancing
the other side.

----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------

Back to
square one.

The Final Bag

The final bag requires some special consideration. Because the sides are getting low, the J piece will not necessarily clear. So I must come before J in order to follow the pattern. You can't rely on using Hold for this as a worst case scenario (eg. TJIxxxx) would also require you to Hold the T. To deal with this problem, you can follow the procedure below.

     I
     I
     I
     I
    JJ
  G JG
GGG JG   G
GGGG GG GG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
GGGGGGGGGG

Stack the I on
top of the J.

     I
     I
     I
     I
OOLLJJTTTZ
OOGLJGSTZZ
GGGLJGSSZG
GGGG GGSGG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
GGGGGGGGGG

Play the
remainder.

     I
     I
     I
     I
----------
----------
----------
GGGG GGSGG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
----------
     I
     I
     I
     I
GGGG GGSGG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG

The end of the
20-bag loop.

But after the first bag of the next loop, we're exactly where we expect to be:

     G
     G
     G
     G
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
GGGG GGGGG
 Z   G
ZZS  GJJLL
ZTSS GJOOL
TTTS GJOOL
GGGGIGGGGG
GGGGIGGGGG
GGGGIGGGGG
GGGGIGGGGG
 Z   G
ZZS  GJJLL
ZTSS GJOOL
TTTS GJOOL
----------
----------
----------
----------
 Z   G
ZZS  GJJLL
ZTSS GJOOL
TTTS GJOOL


5 Bag Solution

A shorter but far more complicated algorithm for Playing Forever in 5 bags was discovered by QM in 2014. It requires 4 piece previews to guarantee success.

This is the minimum possible Playing Forever loop, as a Perfect Clear must use 35 pieces (as the well is 10x10). To avoid parity issues with 5 T pieces, the Bag 2 T is used to clear a single and skim.

First Bag

Build this structure whenever possible.

 Z  IIII
ZZS JJLL
ZTSSJOOL
TTTSJOOL

If necessary, the JILO square can be built in a different order as long as it remains a 4x4 square.

If this structure was impossible (this is rare), place the I to the right.

 Z       I
ZZS JJLL I
ZTSSJOOL I
TTTSJOOL I

Second Bag

The second bag is built differently based on whether the JILO square was completed successfully or not. In either case, the J, L, O, S, and Z pieces are placed identically, like this:

    LOOJ
 Z  LOOJ
ZZS LLJJ
ZZSSIIII
ZZSSJJLL
ZTSSJOOL
TTTSJOOL

Again, the J, L, and O can be flipped if necessary.

The I and T pieces will be placed differently based on the completion of the JILO square in Bag 1.

Case A: The JILO square in Bag 1 was completed.

The T and I pieces should be used to line clear, in this order:

    LOOJ
 Z  LOOJ
ZZS LLJJ
ZZSSIIII
ZZSSJJLLT
ZTSSJOOLTT
TTTSJOOLT


    LOOJ
 Z  LOOJ
ZZS LLJJ I
ZZSSIIII I
ZZSSJJLLTI
TTTSJOOLTI


Leaving the end result of the second bag as this:

    LOOJ
 Z  LOOJ
ZZS LLJJ I
ZZSSIIII I


The T and I pieces can be placed at any time as long as Hold is used to ensure that the T is placed before the I.

Case B: The I piece in Bag 1 was placed to the right.

The I piece should be placed first using Hold to perform a Tetris line clear.

 Z  LOOJ
ZZS LOOJ
ZZSSLLJJII
ZZSSJJLLII
ZTSSJOOLII
TTTSJOOLII


Then, the T piece should be placed in one of these two ways, dependent on the order of Bag 3:

T facing to the left

         T
 Z  LOOJTT
ZZS LOOJ T


T facing to the right

        T
 Z  LOOJTT
ZZS LOOJT


The T and I pieces can be placed at any time as long as Hold is used to ensure that the I is placed before the T.

Determining the direction of the T

With Hold and 4 piece previews, you can see the first 5 pieces of the third bag when placing the T. Based on the order of STZ in the third bag, decide which direction the T should be placed in using the first rule that applies:

1) If TZ comes first in {STZ}, the first two pieces of {IJLO} are OI, and Z comes before I, place facing left.

2) If T comes first, place facing right.

3) If Z comes first, place facing left.

4) If S comes first and is the only STZ piece in all 5 visible pieces, place facing right.

5) If S comes first and T comes second, place facing right.

6) If none of the previous rules apply, place facing left.

Bag 3

This bag is highly situational based on the order of the pieces.

Case A: The JILO square in Bag 1 was successfully completed.

If this is the case, place the pieces like this. Make sure to use Hold on Z to be sure it is possible.

    JJLL
ZZ  JOOL
TZZ JOOL
TTS GGGGI
TGSSGGGGI
GGGSGGGGIG
GGGGGGGGIG


Case B: The JILO square in Bag 1 was not successfully completed.

If this is the case, the S, T, and Z pieces should be placed in one of these two ways:

ZZ
TZZ
TTS     T
TGSSGGGGTT
GGGSGGGGT
T
TT
TZ
ZZS      T
ZGSSGGGGTT
GGGSGGGG T


Decide which one to build based on the T placement from Bag 2.

The I, J, L, and O pieces should be assembled to form a 4x4 square. Note that based on the order, this square can be assembled in whatever arrangement is necessary, including sideways, as long as it forms a square. These are just a few examples of how it could be built.

    JJLL
ZZ  JOOL
TZZ JOOL
TTS IIIIG
TGSSGGGGGG
GGGSGGGGG
    IIII
ZZ  JOOL
TZZ JOOL
TTS JJLLG
TGSSGGGGGG
GGGSGGGGG
    IJJJ
ZZ  IJOO
TZZ ILOO
TTS ILLLG
TGSSGGGGGG
GGGSGGGGG


This can be done without hold unless the order is OIJL or OILJ. In these cases Hold should be used either to modify the piece order to IO{JL} or to O{JL}I. Decide which of these is necessary based on when in the bag Hold is used for the S, T, and Z pieces. This will rarely happen, though.

Bag 4

The I, J, L, and O pieces in Bag 4 are placed into the holes left from the previous bags.

JJJIGGGGOO
GGJIGGGGOO
GGGIGGGGLL
GGGIGGGGGL
GGGGGGGGGL
GLLIGGGGOO
GGLIGGGGOO
GGLIGGGGJJ
GGGIGGGGJG
GGGGGGGGJG


Occasionally, the O piece may be placed in before the J or L on the corresponding side, as long as the I and J/L piece are already in.

In some cases, an I-spin may be necessary if the I shows up late in the sequence.

Placing the S, T, and Z

The first of S/Z and T should be placed like this:

    T
    TT
    TSS
    SS
     T
    TT
   ZZT
    ZZ


The last S/Z piece should be held to the end. 5 pieces of Bag 5 can then be seen in Hold + 4 piece previews. If T comes first in Bag 5's S, T, and Z, then place the S/Z piece like this:

    T
    TT
    TSSZZ
    SS  ZZ
     T
    TT
 SSZZT
SS  ZZ


If S or Z come first in Bag 5's S, T, and Z, place the S/Z piece like this:

    TZZ
    TTZZ
    TSS
    SS
   SST
  SSTT
   ZZT
    ZZ


Bag 5

The T piece and one of the S/Z pieces are placed like this:

    TZZ  T
    TTZZTT
    TSSZZT
    SS  ZZ

The other STZ piece is held until the end.

The 4x4 square on the side is filled with the I, J, L, and O pieces (This can be done in any way as long as the area is filled)

IIIITZZ  T
JJLLTTZZTT
JOOLTSSZZT
JOOLSS  ZZ
IIIITZZ  T
JOOLSS  ZZ


The final piece is placed in with an S/Z spin.

IIIITZZSST
JOOLSSSSZZ


Open questions

Adapting this method to the following situations is left as an exercise for the reader:


See also

  • ST stacking, a method of making back-to-back T-spin doubles

External links