TETR.IO/Seasonal Events

Main article: TETR.IO

TETR.IO holds events for various festivities, usually changing gameplay or visuals.

Fool's Day (April Fools')

Like most of the internet, on April 1st of each year, TETR.IO takes part in the April Fools' Day festivities. This is usually expressed by changing QUICK PLAY's ruleset to one that is both unconventional and impossible to recreate for the normal user, and by changing the "action text" that appears when the player performs actions such as clearing lines, Spins, and combos.

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2020

Illustration of the so-called "Dark Garbage" this year's TETR.IO April Fools' QUICK PLAY was centered around. All players would begin each QUICK PLAY lobby with this field before the countdown even began.

The specific line this block was located on would not abide by the universal rule normally applied in TETR.IO; the line would fail to clear if the line was filled.

Of course, other lines would clear as normal, however, once garbage entered the board, you would not be able to clear it. This created a bias for simply countering pending garbage to ensure none entered your board.

The QUICK PLAY gimmick for April Fools' of 2020 was one singular unclearable block, located on the first row in the third column, that left that row unclearable. Since garbage lines enter from the bottom, once you covered a column on row 1 with a piece, garbage that entered in that column would become unclearable by extension. Furthermore, the garbage multiplier was set to a staggering 9999x, garbage margin time started instantly, the "ALLOWED SPINS" setting was set to "STUPID", and your Next queue was reduced from five pieces to four. The "GARBAGE CAP" setting was set to 1, meaning only 1 line was allowed to enter per piece placed that did not clear lines; likely so you wouldn't top out the instant you received the aforementioned 9999x garbage.

The winning strategy here appeared to be building up a 4-Wide setup, abusing "STUPID" Spins to counter as much garbage as possible, and stalling your way to the end.

The action text this year mirrored that of NullpoMino's action text:

Original action text	Replaced action text
SINGLE	ONE
DOUBLE	TWO
TRIPLE	THREE
QUAD	FOUR
x-SPIN	LARGE x-SPEEN
MINI T-SPIN	TINY T-SPEEN
ALL CLEAR	VERY NICE
BACK TO BACK( x$x$)	MANY TIMES( x$x$)
$x$ COMBO	(unchanged)

The TETR.IO Discord server also changed its name and server icon to match that of the Jstris Discord server. For many, there would be two identical Jstris Discord servers in their server list as Jstris did not return the gesture.

Gameplay footage

• Doremy's "[TETR.IO] Quick Play #8: april fooled (01-04-2020)"

Notes

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2021

Here is an example of each "fractured" piece used in the final QUICK PLAY, starting with the equivalent of the Z tetromino.

This would have been the L piece.

The O tetromino was not changed, although since the ASC table was in effect, O-WIST's were still possible. This proves the system was capable of simply generating the same pieces.

The S piece.

The I piece justified the name of "fractured" pieces for this round. Minos had no obligation to be entirely connected.

The J piece.

The T piece. This generated piece is also commonly known as the F pentomino.

Exactly one year after the previous QUICK PLAY event, shenanigans began once again. This time around, default QUICK PLAY settings were in effect, plus the addition of full All-Spin. However, instead of using guideline tetrominos, all players were served the same 7 randomly generated pieces known as "fractured" pieces. These pieces could be made of anywhere from one to sixteen minos. Each fractured piece correlated to one of the regular seven guideline tetrominos both visually in the next/hold queue and in the "x-WIST" action text.

Due to the randomly generated nature of these pieces, the Super Rotation System kick table was not a good fit for this mode. Hence, the dynamic "ASC" kick table, originally created for winterNebs' Ascension, was used in its stead. The kick table might not have been the only bit of inspiration taken from Ascension for this mode; Ascension's "Mutation" mode generates very similar pieces on later mutation levels. The ASC kick table was already implemented into TETR.IO in update 0.7.2-pre0 released the year prior. However, the ASC kick table did not contain any 180 kicks, so custom additions were made for the event.

The winning strategy here differed from round to round depending on how favorable the fractured pieces generated. More than likely, pieces would simply be too unorthodox to legitimately play the game with, so good knowledge of the lock delay mechanics went a long way towards stalling your way to the end.

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The T-Wist in its first appearance.

The action text switches this time around took a more simple approach to displaying how many lines a single piece cleared:

Original action text	Replaced action text
SINGLE	(unchanged)
DOUBLE	SINGLE x2
TRIPLE	SINGLE x3
QUAD	SINGLE x4
PENTA, HEXA, HEPTA, etc	SINGLE x$x$
KAGARIS	KAGARIN IS CUTE
x-SPIN	x-WIST
MINI T-SPIN	MINI T-WIST
ALL CLEAR	BRAVO
B2B x$x$	CHAIN x$x$
$x$ COMBO	(unchanged)

The "T-WIST" text was likely a reference to GlitchyPSI's YouTube video titled "A casual day with a twist.". The "BRAVO" text likely drew inspiration from the Tetris The Grand Master series, where an "All Clear" is called a "BRAVO" in earlier games. The "CHAIN" text could be a reference to the Puyo Puyo series, but more likely it is a simplified name for the Back-To-Back Chaining mechanic.

The TETR.IO Discord server did its part in the tomfoolery by changing its name to a self-aware violation of the | branding guidelines by changing its name to "Tetr.IO". Furthermore, the moment 1st April for the CEST time zone arrived, the following announcement was made in #news parallel to the update that changed the QUICK PLAY ruleset:

The "JSTRIS handling mode" toggle. Activating it would produce the visuals shown above.

“Version 6.0.4a is now live.
➔ Added JSTRIS handling mode!
　-> It makes your handling exactly like Jstris handling. Find it in CONFIG -> HANDLING
➔ I couldn't be bothered to write the rest of the patch notes sorry”

—osk

This "Jstris handling mode" manifested as a toggle in the handling category of the config. Activating it would remove the frame based indications of how DAS and ARR were configured, and replace them with counters that tracked milliseconds, just like Jstris. Changing your ARR value would impact your DAS value, specifically adding your ARR to your DAS. TETR.IO DAS/ARR is not the same as Jstris DAS/ARR, and the update that "fixed" TETR.IO's DAS. suggests this addition workaround for users with positive ARR Aside from the visual changes mentioned, this toggle effectively did nothing to change TETR.IO's handling.

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Gameplay footage

• Lilla Oshisaure's "TETR.IO with bad pieces" stream
• JG Zeem's "[Tetr.io] Tetra league JJ_ZEEM vs HARROMAN" video. If you needed proof that action text was globally changed, here it is. It didn't matter whether you played Zen mode or Tetra League, a T-Spin was a T-Wist that day.
• Sretzo's "Tetr.io | Funny looking pieces (April Fool Super Lobby)" video

Notes

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2022

Compared to the previous April Fools', 2022's foolery came and went to little official fanfare. Lacking any external announcement over the server maintenance, aside from the standard ten minute timer in-game players are subject to, the event made up for this underwhelming aspect by lasting from March 31, 8:00 PM UTC to April 2, 12:00 PM UTC, a total of 40 hours. This subdued deployment was due in part by extended development time away from TETR.IO's main codebase, with development efforts going towards the still pending "Character System" update, and by osk's unfavorable schedule at the time, which did not permit for extended debugging if launched at the normal times.

The extent of the April Fools' update, titled "version 6.2.0a", applied only to QUICK PLAY. No special action text was supplied, nor did any modification of the ingame CONFIG occur. QUICK PLAY's config was similar to standard settings, bar the usage of the ASC kick table and immobile All-Spin, with the addition of "Voidholes". Every round, one to three Voidholes spawned on the lower half of the matrix, spawning in the same location for every player. These destructive yet indestructible nuisances affect both your static field and your active piece. If either intersects a Voidhole, be it by piloting an active piece into one, accepting garbage, or clearing lines, the offending mino is destroyed.

When part of an active piece is destroyed, the piece remains controllable. However, should you continue to drive the piece into a Voidhole, it will eventually be destroyed entirely. Destroying your entire active piece still causes garbage to enter, so you cannot use this method to stall indefinitely.

When your stack is pushed up into a Voidhole by garbage, the Voidhole destroys all minos that would pass through it. The upper limit of three Voidholes prevents scenarios where no garbage can ever cause a top-out, as an I-piece spawns 4 columns wide.

Curiously, if the stack is pushed down two or more rows by a clear, the Voidhole will only consume the higher mino. This is likely an oversight, as clearing rows below Voidholes proves to be a difficult challenge while the Voidholes themselves remain unclearable.

The simple fact of Voidholes being unclearable makes the challenge similar to that of the first April Fools'. Unlike that event, however, the winning strategy here involved using your Voidholes to attain trivial 1-row-tall All Clears by partially destroying every piece into pseudo-monominos or pseudo-dominos during the opener phase, and then relying on efficiency to cancel garbage. L or J pieces were important for downstacking above Voidholes, as using an I-piece would destroy the entire piece. Late into each round, a good understanding of ASC rotation was crucial to surviving under high gravity.

Gameplay footage

• Wumbotize's "April Fools Day 2022 on Tetr.io" match
• Strode's Various Game's "April 1st, 2022 April Fools' Day Quick Play [TETR.IO]" stream archive
• Stepperステッパー's "April Fools Tetrio" video
• Edge's "How to WIN April Fools TETR.IO" clip
• am'bush' Gaming's "2022 April Fools' Quickplay is insane! | TETR.IO" extended gameplay

Notes

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2023

2023 featured Kaliente mode, known initially as "?????" mode. As again, there were initially no announcements or patch notes regarding this April Fools'. After April 1st, settings were updated to reflect the "real" name of the mode. The mode was made available site-wide for custom rooms around March 31st, 11:50 PM UTC. Aside from the unique new game mode, action text and other CONFIG settings remained untouched. While initially planned to only last for the day, Kaliente remained available for use in custom rooms until 6.3.3's release about 11 days after April Fools'. After being removed from QUICK PLAY, the Kaliente setting tooltips were replaced with properly descriptive ones.

A few differences are immediately apparent in Kaliente. There is now a HP value displayed under your board and on the right as a bar. This transforms the win condition into one where, instead of being the last player to top out, you must be the last player with remaining HP. If you top out, you instead lose some HP, and your board will be partially cleared leaving residue to clean up. When High or Ultra graphics are enabled, the knock-out animation is changed to a much more explosive one, in which the board shatters into several pieces in a psuedo-3D effect.

When you receive garbage, a random column is highlighted to indicate that you may perform a "parry". By clearing lines with any part of your piece above the highlighted column, your line clear gains an attack bonus. parries may be chained off each other: for example, if one player parries an attack, it becomes a "double parry", then if that attack is parried, it becomes a "triple parry" and so on. The more times any one parry is bounced around, the more damage it deals to your HP if you accept any of its garbage. When a parry is pending, you can tell how long the chain is by the colour your board becomes.

The next parry columns are indicated by four arrows, each different colors, at the bottom of your board. When a parry column is active, a number indicates how long of a parry chain you recieved.

When parries are chained, you can tell how much danger you are in by looking at your board's color or the aforementioned number. The following table shows each parry tier:

Concurrent parry number	Ingame name for parrying it	Associated color
#1	PARRY!	Reddish pink
#2	DOUBLE PARRY!	Cyan
#3	TRIPLE PARRY!	Orange
#4	QUAD PARRY!	Green
#5	PENTA PARRY!	Dark blue
#6	HEXA PARRY!	Magenta
#7	HEPTA PARRY!	Very light cyan
#8	OCTA PARRY!	Very light cyan
#9	ENNEA PARRY!	Very light cyan
#10	DECA PARRY!	Very light cyan
#$x$	$x$-PARRY!	Very light cyan

Many arbitrary variables were made available for players to change. Here is a table of the available options as well as the QUICK PLAY defaults.

Option	Internal name	Default QUICK PLAY value	Post-Fools' tooltip	April Fools' tooltip
Enable Kaliente	game.options.kaliente	ON	Enable the temporary Kaliente mode, where you parry garbage to lower your opponent's HP.	If enabled, your computer will blast. ← What?
Starting HP	game.options.kaliente_hp	750	The starting HP in Kaliente mode.	What? There was treasure. And it's right here. [I point to my heart.]
Multiplier	game.options.kaliente_multiplier	1	Global multiplier of all HP damage.	There! Go fetch!
Margin time	game.options.kaliente_margin	0	Time in frames after which the damage multiplier for Kaliente goes up.	↑Yoshino Powerhiko
Increase	game.options.kaliente_increase	0.0085	Amount with which the damage multiplier increases per second.	You're banned from the internet from now on.
Topout cost	game.options.kaliente_topout_cost	0.3	Index of how much HP a topout costs.	Shizuru is happily performing photosynthesis.
Punishment cost	game.options.kaliente_punishment_cost	1.5	Index of the HP cost of tanking lines with your piece in the parry line.	I doubt that makes any sense to you, but it doesn't make sense to me either so there's nothing I can do.
Garbage impact	game.options.kaliente_amt_cost	1	The amount of impact the size of an attack (in garbage) has on its HP damage.	The impact of garbage like me.
Parry power	game.options.kaliente_parry_impact	2.15	The power (as in, 𝑛^x where 𝑛=this setting and x=the parry power) of parrying to the damage.	If this was a story... would I be like a protagonist?

The winning strategy for Kaliente mode was not very clear-cut. In theory, players could predict parry columns and actively engage with the systems put forth, but in practice, players may have felt more inclined to farm large Back-To-Back Chains and cancel all incoming garbage, thereby ensuring no damage entered their board. The chaotic nature of QUICK PLAY made it hard to determine when and how much garbage one player might receive after a point. The lower starting garbage multiplier and longer garbage travel time during the event, combined with Kaliente's large starting HP pool, made QUICK PLAY rounds last a long time. This meant rounds would go into Margin Time, at which point surviving became reliant on RNG as all attacks would hit very hard.

Gameplay footage

• ICLY's TETR.IO April Fools Quickplay Begineer's Gameplay match
• Wumbotize's It's April Fools Day 2023 on Tetr.io match
• Talon S.'s TETR.IO - Winning Quick Play During the April Fools' 2023 Event match
• am'bush' Gaming's 2023 April Fools' Quickplay is awesome! | TETR.IO stream
• LTS's TETR.IO APRIL FOOLS stream

Notes

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2024

2024's event had no coordinal announcements and ran from March 31st, 10:00 PM UTC, and ended with the release of 6.4.4 on April 2nd, 3:00 PM UTC. QUICK PLAY had an implementation of bomb garbage similarly to Tetris Battle, where garbage generates as solid lines with an exposed core in one column, shown as a stylized ☢️. Placing a piece directly on top of this exposed core would clear the row of garbage, as well as subsequent rows underneath with the same bomb column. This action counts as a line clear, and thus, preserves combo/Back-to-Back status. Bombs also follow change-on-attack generation, much unlike Tetris Battle. This allows for line clears and T-Spins beyond Quads to be scored. Extended line clears would send the following:

Line Clear	Garbage sent
Quad	4+B2B
Penta	5+B2B
Hexa	6+B2B
$x$ rows cleared	$x$+B2B
T-Spin Double	4+B2B
T-Spin Triple	6+B2B
T-Spin Quad	10+B2B
T-Spin Penta	12+B2B
T-Spin Hexa	14+B2B
$x$ rows cleared with a T-Spin	$2x+2$+B2B

All players were allowed to access this new garbage mode in custom rooms by running /set options.usebombs=1 in the chat as a host on April Fools'. Bombs were solidified as a room option in 6.4.4, making them a permanent addition. In addition to bombs, two new random bag types were introduced for use in custom rooms or solo custom games: 7+1-bag and 7+2-bag. These use the standard Random Generator method, with 1 or 2 extra arbitrary pieces shuffled into each bag. This change makes openers far less reliable, and in most cases, impossible to perform.

Notes

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2025

2025's event was the first to take place in the reworked QUICK PLAY mode. With it came the new "PENTR.IO" mod, and its reversed version, "A Fool's Errand", unlocked by climbing a total of 2500m with the base mod.

When PENTR.IO is enabled, the familiar 7-bag of tetrominos is replaced with a much more unwieldy 18-bag of pentominos. ASC rotation returns for these pieces. Additionally, QUICK PLAY's background is replaced with mockup sketches drawn by Garbo, and the board is recolored to white. In a Duo, all revive prompts are replaced with a single prompt to clear a certain number of lines. This number increases by floor and per revive.

When reversed PENTR.IO is enabled, the pentominos are 'upgraded' to a near unusable 35-bag of hexominos. These were each named after stars, a list of which can be found here. One of the few viable strategies was to stall for clean garbage, clear using the "I6" pentomino, stall using the climb speed until floor 2, then finally clear lines to pass the threshold.

Two achievements were available during the event: "THE FOOL" for highest altitude reached with the PENTR.IO mod, and a hidden issued achievement called "A FOOL'S ERRAND" for reaching floor 2 with the reversed PENTR.IO mod.

Notes

Holidays

2021

Ingame image of TETR.IO during the holiday seasons.

“Christmas is almost here! The entire TETR.IO team would like to wish you Happy Holidays!
Please enjoy a slight reskin of the game to fit the mood! Also, Supporter gifts are 25% off! Could make a nice gift!”

—osk, December 19th, 2021

Following the trends of other services, TETR.IO also partakes in seasonal redecorating. Between December 19th, 2021 to January 4th, 2022, there was a full change-up of backgrounds, board appearance, accent colors, and the addition of snowy particles. This reskin was also responsible for developments in the modularity of TETR.IO customization, being the first deployment of piece/ghost skin mix-and-matching and introducing entirely new textures to the internal "board.png" file, doubling its size, which was later ditched when the update was reverted.

“Happy holidays from the TETR.IO team!!! Please enjoy the festive spirit we've given the game again this year!
Feeling grinchy? You can disable the festive skin in Config this time around.”

—osk, December 21st, 2022

2022

Returning for 2022, the year's holiday reskin was much more fundamental in altering TETR.IO's look and feel. With a new, animated queue which dynamically flipped between two frames depending on how quickly you played, the counters to the side of the board also shook slightly upon each update. Attacks were replaced with snowballs, and the grid showed a checkerboard pattern. Since this update changed much more than the last year's, players were able to toggle it via a setting at the very top of Config. The festivities lasted from December 21st, 2022 to January 8th, 2023.

“Happy holidays from the TETR.IO team! Please enjoy the festive spirit added to the game!
This time, there's something quite special courtesy of @doktorocelot , do turn up the volume!”

—@tetriogame, December 17th, 2023

2023

Back again for 2023, major additions included newly remixed main menu and Blitz songs, the accumulation of snow on your board, and an omnipresent but configurable snowstorm in the menus. Assets that were made for 2022's celebration returned, and most customizations could be disabled using the same toggle at the top of the config. This event lasted from December 17th, 2023 to January 8th, 2024.

2024

The 2024 holidays featured a return of the snowy decorations and custom Blitz soundtrack, remastered for 2024. Additionally, the limited-time mod "Snowball Board" was added to QUICK PLAY. With this mod, the board starts at 4x4 and grows larger after the player clears a certain number of lines. The maximum size it can reach was 20x20, twice as wide as the standard board.

An achievement was added for the player's highest score obtained with the mod, which is no longer obtainable. Players who competed with the mod received a badge with their top floor and final rank after the event ended. The event lasted from December 5th, 2024 to January 1st, 2025.

5,000,000 Blast

See also: TETR.IO Badges: 5,000,000 Blast

In celebration of TETR.IO reaching five million players, a temporary SOLO game mode was released parallel to the occasion. This mode, subtitled "5,000,000 BLAST" ingame, existed for exactly 2 weeks. The first week held a competition for high scorers. All users who placed 1000th or higher would receive a special badge, as well as free durations of Supporter.

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An illustration of two line clears made during this event, in this special mode. The first Quad is a COOL!! line clear, as no recent line clears have been made on the rightmost column. The 2nd Quad is a REGRET line clear, as it repeats the first one to the column.

The mode itself was a race to simply attain 5,000,000 points or more as quickly as possible. Games would start with an extremely low score multiplier, and this hidden multiplier would silently increase exponentially as the game went on. Players did so while actively working around a system of "originality" which rewarded unique line clears to the session, and punished duplicate line clears. Internally, this system was represented by a sequence of "buckets", one for each of the 10 columns in a TETR.IO board, and one for every action listed in the score table above. That is to say, the following actions would be judged in combination with the row you do them in:

• Singles, Doubles, Triples, and Quads.
• T-Spins: both Mini T-Spins and full T-Spins were judged separately.
• T-Spins which do not clear lines also count as a separate action.
• All Clears: notably, these were judged strongly negatively if cleared. Specifically: after doing two All Clears, any more will impose an immediate, permanent deficit on your internal originality variable, decreasing it by 9.15 units. This, in turn, led players to receiving negative score, eventually going below 0 points so long as one continued this behavior.

“COOL!! if
・total originality increase this placement exceeded 4 + {amt of lines cleared}
・originality is now more than 8 (to prevent first move from always being COOL!!
REGRET if
・you lost originality in any way (by trying to take from a near-empty bucket, or by doing excessive PCs)”

—osk "5 Million Blast Research". TETR.IO Discord server. March 8, 2022. Retrieved .

This system was displayed to the player with the terms "COOL!!" and "REGRET" onscreen, borrowing heavily from the TGM series's section time call-outs. While these were helpful indicators to nudge players in the right direction and were overall beneficial to the mode's playability, they were not absolute indicators of optimal gameplay and were based upon somewhat arbitrary cutoffs. The top 1000 submissions in the leaderboard hovered near the 200-300 blocks placed statistic. As a time based mode, naturally, you would want to lower the amount of required pieces to get more done with less inputting, so, abusing COOL!! line clears was a must-have for the high ranking players.

Lover's Day (Valentine's Day)

In 2025, TETR.IO celebrated Valentine's Day with an event formally known as Lover's Day. This event lasted from February 13th to the 20th. During the event, players could ask any mutual friend to be their TETR.IO Valentine, which they would be irreversibly paired with for the rest of the event, should they accept. All partnerships were considered public information, being displayed on your profile(s). In addition, a complete list of your mutual friends' pairings was also shown in the QUICK PLAY menus. At the end of the event, both players received a badge according to their final ranking and eligibility in the Lovers' Promise achievement.

Additionally, the reversed version of Duo, "Bleeding Hearts", was available during the event. Unlike other reversed mods, it had no unlock requirement.

When enabled, both player's attacks are halved and injected directly to their partner's board, bypassing the garbage queue. When one player tops out, climbing is blocked and the surviving player injects garbage to themself until the player is revived. It also has a set of unique Fatigue effects with some being positive.

The Fatigue effects are as follows:

Time	Effect	Message
1:00	Garbage becomes a bit messier	THE RELATIONSHIP STAGNATES...
1:30	Garbage becomes messier	INSECURITIES GROW STRONGER...
2:00	Garbage becomes much messier	(Player 2) FEELS NEGLECTED...
2:30	Garbage becomes a bit cleaner	(Player 1) SUCCESSFULLY APOLOGIZES...?
3:00	Garbage becomes much cleaner	THINGS ARE BACK TO HOW THEY SHOULD BE...!
3:30	Garbage becomes messier	THE WEIGHT OF WORDS UNSPOKEN...
4:00	Garbage becomes much messier	"WHY CAN'T YOU JUST LISTEN TO ME?"
4:30	Revive difficulty increased	"THIS IS ALL YOUR FAULT."
5:00	Garbage becomes cleaner	(Player 2) MAKES THE SAME PROMISE AGAIN...
5:30	+4 permanent garbage	"THIS TIME WILL BE DIFFERENT."
6:00	Garbage becomes much messier	SOME HABITS CAN'T BE BROKEN...
6:30	Garbage becomes messier	ALL TRUST HAS WITHERED AWAY...
7:00	Garbage becomes messier	(Player 1) SETS AN ULTIMATUM...
7:30	Garbage becomes messier	(Player 2) CONTEMPLATES THEIR WASTED EFFORT...
8:00	Receive 25% more garbage	ONE LAST PAINFUL ARGUMENT...
8:30	You can no longer revive	GOODBYE.
9:30	Garbage becomes much cleaner	"I MISS YOU"
10:00	Garbage becomes a bit cleaner	WHAT IF...?
10:30	+12 permanent lines (total 16)	...

(Player 1) and (Player 2) are replaced with each player's username.

Notes