Tetris Stardust

Tetris Stardust
Tetris Stardust icon
Publisher(s)	Tetris Online Japan, Inc.
Platform(s)	Web (Silverlight)
Release	c. December 2009
Gameplay info
Next pieces	5
Playfield size	10 × 20
Hold piece	Yes
Hard drop	Yes
Rotation system	SRS

Tetris Stardust is an online free-to-play Tetris game released in Japan by Tetris Online Japan, Inc.

Gameplay

Tetris Stardust features a single game mode in which the player must score as many points as possible in 40 lines. It uses a modified version of the Guideline ruleset.

The game features spin recognition for all tetromino types and a Spin Rank system to reward the player for performing a variety of twists. Performing multiple unique twists with the same piece will award higher spin ranks.

Star Marks are randomly placed on the playfield. When all spaces with Star Marks are occupied, an avalanche will be triggered. This will effectively break every piece on the playfield into individual blocks and cause them to fall. Additional points are awarded for clearing lines with avalanches.

Rotation System

The rotation system in Tetris Stardust is SRS with some modifications to allow wall kicks with the O tetromino. Normally, the O tetromino does not move when rotated, but if one of the following checks succeeds, the game will bypass basic rotation and perform a wall kick.

• If rotating left, the space directly underneath the lower-right block must be occupied
• If rotating right, the space directly underneath the lower-left block must be occupied

O Tetromino Wall Kick Data

	Test 1	Test 2	Test 3	Test 4
CW	( 1, 0)	( 1,-1)	( 1,-2)	( 2,-1)
CCW	(-1, 0)	(-1,-1)	(-1,-2)	(-2,-1)

Scoring

Scoring is mostly based on Guideline scoring. However, the logic which calculates the score for a piece actually yields two main values: a Finish Score, which includes line clear, spin (not Spin Rank), and combo points; and a Total Score, which includes all of these plus perfect clear, hard drop, and soft drop points. Both of these values are used to increment the player's score, which causes all line clear, spin, and combo points to be doubled.

Additional values are defined for certain spins performed with non-T tetrominoes and the unique "Spin Rank" mechanic.

Below is the scoring table including both the internal values and the effective scores after accounting for the score doubling quirk.

Action	Internal Score	Effective Score
Single	100	200
Double	300	600
Triple	500	1000
Tetris	800	1600
T-Spin Zero1	400	800
Spin Zero	100	200
Spin Single	800	1600
Spin Double	1200	2400
Spin Triple	1600	3200
Spin Mini Single	200	400
Spin Mini Double2	600	1200
Combo	100 × combo count
Soft Drop	1 × cells
Hard Drop	2 × cells
Perfect Clear3	0
Back-to-Back	Action Score × 1.5

¹ There is no separate score value defined for a T-Spin Mini Zero. Because of this, it scores the same as a T-Spin Zero (800), which is significantly more than a T-Spin Mini Single (400). This is most likely an oversight.
² Displayed in-game as "(Piece)-Spin Mini-W" for non-T pieces. T-Spin Mini Doubles do not display anything, but still award 1200 points.
³ While the game recognises and displays Perfect Clears, there is no score value defined for them.

Spin Rank

Spin Rank may be awarded after performing a wall kick. For a kick to be eligible, it must move the active piece below its previous lowest position. If this check succeeds, the game will then compare the surroundings of the new rotation state with a list of Spin Rank configurations. Each configuration contains a list of block positions which must be occupied, and an associated Spin Rank (either B or C) if the check succeeds.

If a match is found, then Spin Rank will be awarded depending on which kick was triggered:

• Basic rotation and Kick 1 do not award Spin Rank.
• Kick 2 awards the base Spin Rank of the first matched configuration.
• Kicks 3 and 4 award a +2 bonus to the configuration's base Spin Rank.

If multiple kicks are performed sequentially, the Spin Rank of the previous kick will add a bonus:

Prev. Rank	Bonus
E, D, C	+1
B, A-	+2
A, A+, S-	+3
S, S+	+4

Spin Rank is then scored per kick based on this table. Note that this is completely separate from a line clear's action score and has no influence on Back-to-Back bonuses.

Spin Rank	Points
E	50
D	100
C	200
B	400
A-	600
A	800
A+	1000
S-	1400
S	1600
S+	1800

If a kick is eligible for Spin Rank but does not match any of the rotation state's Spin Rank configurations, the default of no Spin Rank (corresponding to an internal value of -1) will be awarded. This is boostable by kick bonuses and is the only way to achieve ranks E and D.

Spin Rank also influences spin recognition for non-T spins. Spins are considered "Mini" if the Spin Rank of the kick triggering the spin awards a B rank or lower.

For the T tetromino, Mini spins are the same as other Guideline games, except there is no special case to upgrade Mini T-Spin Doubles if they were performed with a rotation's final kick.

Star Dust Avalanche

At the start of a game, two Star Marks are randomly placed on the playfield. Covering every Star Mark at the same time will trigger an avalanche known as a Star Dust, breaking every piece on the playfield into individual blocks and applying gravity similar to a cascade. With each Star Dust, a new random set of Star Marks are placed, with one additional Star Mark being added.

There are two main types of Star Dust:

• Star Dust - Triggered by placing a piece to cover the final Star Mark
• Combo Star Dust - Triggered by performing a line clear which moves higher portions of the stack to cover the remaining Star Marks

Scoring for a Star Dust avalanche (if it clears at least one line) is calculated as follows:

$A=(500+1.5F+0.75S+C)\times 1.35^{L}\times P$

• A is the total avalanche score.
• F is the Piece Finish Score, which includes the internal base values of the line clear, spin, and combo performed with the triggering piece, or zero if no line clears or spins were performed.
• S is the Piece Spin Score, which is the total number of Spin Rank points accumulated by the triggering piece.
• L is the number of lines cleared by the avalanche. This does not include lines cleared by the triggering piece.
• P is 2 if the avalanche ends with a Perfect Clear, otherwise it is 1.
• C is the Combo Star Dust bonus. For a regular Star Dust, this is zero. For a Combo Star Dust, C is calculated as follows:

$C=(F+S)\times {M \over 5}$

• M is the number of Star Marks newly covered as a result of the triggering piece and its line clear.

When the avalanche score passes certain score thresholds, special text will be displayed. For example, if a Star Dust avalanche scores between 5,000 and 9,999 points, the text "5000UP" will be displayed. Below is a full list of these score thresholds:

• 5,000
• 10,000
• 20,000
• 30,000
• 40,000
• 50,000
• 100,000
• 300,000
• 500,000
• 1,000,000
• 3,000,000
• 5,000,000

The highest scoring Star Dust, the line clear that triggered it, and its score are displayed on the results screen at the end of the game. If it is a Combo Star Dust, this will be specified as well as the number of stars covered by the line clear. For example, if the player performs a T-Spin Double that causes the stack to cover 2 stars, and that is the highest scoring Star Dust in that game, the results screen will display "T-Spin Double Combo Star Dust 2 Stars".

External links

• Tetris Stardust archived on tetrisonline.pl (requires Silverlight)