|Platform(s)||Web (Native)[note 1] |
Desktop: Windows, Linux, macOS[note 2]
February 19, 2019
January 31, 2020
March 22, 2020
|Latest release||6.1.5 / January 9th, 2022[note 3]|
Desktop V8 / March 7th, 2021
|Next pieces||5 (default)|
|Playfield size||10 × 40 (default, modifiable in solo custom games)|
|Hold piece||Yes (default)|
|Hard drop||Yes (default)|
|Rotation system||SRS, SRS-X, SRS+, ARS, NRS, ASC, Tetra-X, None|
TETR.IO is a free-to-play online multiplayer and single player game developed by osk. Players can play against friends and foes all over the world and claim a spot on the leaderboards, found in the TETRA CHANNEL.
TETR.IO offers multiplayer and solo play. There are currently four single-player modes and two multiplayer modes.
In multiplayer, the player can play matches against other players. A player can choose to play in the game's Quick Play room where players can play a match with default settings. The Custom Play option allows for creation of custom rooms, with the ability to change settings for the room such as spin bonuses, player limit, the amount of next pieces shown, and others. The player can view public rooms in the Room Listing menu, if the host of the room created it as a public room. Each multiplayer game with 3 or more players plays similarly to Tetris 99 along with alike targeting options, minus the ability to manually target by default, included. A garbage/gravity margin time system is also in the game, in which the amount of garbage sent/gravity present on the active piece is multiplied more and more after a static period of time.
Combo System: "Multiplier"
All multiplayer TETR.IO matches utilize a very different combo table than other Tetris games and clones. This system is known as the multiplier system in the community, and its purpose is pretty simple. It heavily nerfs the previously overpowered "four-wide" combo setup, and awards combos with Quad or T-Spin finishers with a large spike. This system cannot be disabled or altered in any way, and it is present in every online match including Quick Play, TETRA LEAGUE, and Custom Rooms.
Back-to-Back Chaining was introduced in the 2.3.2 update released on the 24th of April, 2020 as an experimental feature which quickly became a popular quirk for many, and made its way into being a default mechanic the next update the day right after it was introduced.
To take advantage of this mechanic, one must preform several "difficult line clears", meaning Quads and T-Spins, without clearing singles, doubles, or triples inbetween each difficult line clear. This is known as a Back-to-Back, and they are rewarded in other Tetris games and clones by adding one line of garbage to an attack.
TETR.IO takes this idea one step further, and actually rewards the player according to how many Back-To-Back line clears one can clear in a row:
|Range of concurrent, unbroken "difficult line clears" done in a row||The corresponding visual "B2B" indicator shown||Garbage added to the line clear's normal garbage amount|
|1-3||(none shown)-B2B x2||1|
|4-8||B2B x3-B2B x7||2|
|9-24||B2B x8-B2B x23||3|
|25-67||B2B x24-B2B x66||4|
|68-185||B2B x67-B2B x184||5|
|186-504||B2B x185-B2B x503||6|
|505-1370||B2B x504-B2B x1369||7|
Supposedly, this system stretches on into infinity, as it seems to progress similarly to a square root function. These values were posted by osk in a pinned message on the official TETR.IO Discord server's #tetrio channel.
This system can be disabled in a custom room by the room host, with the small ON/OFF toggle at the bottom of the game settings labeled "ENABLE BACK-TO-BACK CHAINING".
Garbage Travel Speed: "Passthrough"
As another big deviation from other clones and official games, this mechanic allows two players to send garbage to each other without negating the garbage sent if timed correctly. If this system is enabled, a timer of 20 frames, or 333 milliseconds plus a variable amount of network lag, begins whenever any player sends garbage. During this timer, the garbage sent is untouchable, and any garbage sent from the player this garbage is going towards will pass through to the enemy targeted without interrupting the garbage coming their way. In this case, a special sound will play, and the garbage sent will land on the user targeted entering their garbage queue.
As of 6.1.2, hosts must opt-into this system, by toggling the "GARBAGE PASSTHROUGH" option, which is disabled by default, under the "GRAVITY AND MARGIN TIME" category. This mechanic has, historically, gone through many controversies leading to its removal as a mechanic by default -- please refer to the Professional Concerns section for more info.
TETRA LEAGUE is the ranked mode in TETR.IO. As of its public release, players must be registered and their level must be at least level 10 to enter, and anonymous players cannot play this mode. When the mode was first released, INFDEV testers and supporters were only eligible for the mode. Each game of TETRA LEAGUE is a 1v1 match, with a first-to-3, FT5, or FT7 format based on one of the players' rank. The rating system is called Tetra Rating, which is based on Glicko-2. TR increases for each win and decreases for each loss exclusively. When playing this mode for the first time, the player must play at least 10 ranked matches, referred to as the "rating games", to display their TR. A letter rank is assinged to all players with less than 100 RD (short for Rating Deviation) based on their percentile in the leaderboards. RD normally decreases to a lower limit of 58 RD every time the player plays a TETRA LEAGUE game, and slowly increases at a flat rate of 1 RD per day after a week of inactivity, leading to a maximum of 350 RD.
The game also includes solo modes, two of which have leaderboards: 40 Lines and Blitz. For all modes except Zen, Stride Mode can be activated. This option speeds up the countdown by changing it from "3-2-1-Go" to "Ready-Set-Go", enables tap-to-retry (by default, players will have to hold the retry key to do so), reduces the time to exit a solo game by holding the forfeit key, and speeds up all animations at the start and end of games. 40 Lines and Blitz have an option called Pro Mode which shows the finesse counter. In 40 Lines, it also displays the number of lines remaining on the board and the key presses per minute on the left.
All solo modes have a scoring table similar to the ones seen in guideline games. It goes as follows:
|Line Clear/Action||Points Scored|
|T-Spin Mini Single||200|
|T-Spin Mini Double||400|
|Back to Back "difficult" line clears||(where is the point value of the line clear)|
|Combos||(where correlates to the current combo value)|
All point values are multiplied by your current level, except for Zen mode, where no level multiplication occurs. If a change to the "Allowed Spins" option to "Allspin" or "Stupid Spin" takes place in a solo custom game, all spins will count for the same amount of points as T-Spins would, and I-Spin Quads would count for 2600 points.
In addition to this table, there are flat rates, which are not multiplied by level, for simply dropping a piece as well:
|Action Taken||Points Scored|
|Hard Drop||2 per cell dropped|
|Soft Drop||1 per cell dropped|
In 40 Lines, the objective is to clear 40 lines as fast as possible. In accordance to TETR.IO's delayless vision, no "stacking style" limits your speed thanks to the lack of ARE and the presence of "0ARR" handling settings.
|Level||Lines required to level up(total lines cleared)|
Higher is possible, but no one has achieved any level above 13 on the official top 1000 Blitz Leaderbaords. You can replicate this leveling scheme with the "leveling speed" option in custom solo games set to "0.42". This value was ripped out of a .ttr file of a Blitz replay. In it, it defines the level speed value and can be technically read with any conventional text editor, as the file itself is plain text JSON data.
Zen is an endless mode with no top out game overs and a special level system, inspired by the mode of the same name from the Bejeweled series, starting with Bejeweled 2. Gravity is adjustable by the player, and garbage is toggleable from a menu accessible after hovering over the right side of the window. It can also be played while waiting for the next match in Quick Play, Custom Rooms, or while waiting for your next opponent in the TETRA LEAGUE queue. Experience Points are gained at a static 100XP per minute whilst in Zen mode. This caps to a maximum of 3000XP per session, meaning one can only gain Experience Points for a maximum of 30 minutes before needing to forfeit and re-enter Zen mode to continue receiving Experience Points.
The player can create their own solo mode with most of the settings carried over from the Custom Play room creation menu. By default, the Custom Room options are set to match those of the fixed-goal Marathon mode from Tetris games.
- Main article: TETR.IO Badges
Badges are simple graphics placed on a specific and registered user's userpage or player card signifying that user's achievements. There are 5 badges obtainable from a new account without administer or moderator intervention, and 20 badges placed on users specfically for something verified by an admin/moderator, such as winning a tournement or having an account in the INFDEV devlopment phase.
Starting with 0.6.0-pre0, TETR.IO made its first non-guideline modification to the kick table, adding a custom 180 kick table. This table is relatively resilient to abusable spins, however there is plenty of room for handy L and J tucks with this system.
|In a situation shown to the left, limited to guideline clockwise and counterclockwise spins, the only "clean" downstack would be building up a wall on the left side of the field and spinning a Z in.|
|However, if you have a 180 key bound and a L tetromino in the playfield, simply soft drop,|
TETR.IO also includes a separate kick table known as "SRS-X" that can only be enabled at the request of a room host or a solo custom player as it is not the default kick table. SRS-X is known for its "more powerful 180 spins" such as the ones seen in NullpoMino or Heboris. Aside from that, it is standard SRS with no modifications.
As of version 5.0.0, TETR.IO uses a modified version of SRS as the default option, in which the I wall kicks are symmetrical along the y-axis, similarly to TGM3; however, the left-side kick tables are mirrored instead of the right side. This allows certain situations that are impossible in regular SRS to be made effectively.
|As in Guideline SRS, the shown placement can be achieved by rotating clockwise.|
|In the symmetric position, this can now be achieved by rotating clockwise or counter-clockwise.|
The ingame TETRA CHANNEL contains leaderboards for 40 Lines and Blitz with replays, as well as personal bests and their replays in either Blitz or 40 Lines, personal TETRA LEAGUE replays, and your last ten submitted solo replays in the "ME" section. The Players screen lists the top players sorted by their league rating or by the total amount of experience points (XP) accumulated throughout the game. Unfortunately, due to technical limits, all of these leaderboards are capped at the hundredth player/replay.
In addition to the features above, it also shows players who are currently streaming with the TETR.IO category on Twitch. The Tetra News section displays achievements done by players, such as reaching the top ten in either solo mode with a leaderboard, or winning one of TETR.IO's many partnered tourneys. There is also a simple "search bar" at the top of the TETRA CHANNEL, where you can input specific replay IDs or URLs to access them, as well as access specific player cards with an exact player name.
Standalone TETRA CHANNEL
After the 5.0.0 update, a standalone TETRA CHANNEL site was released. This site would accomplish most of the same things the ingame TETRA CHANNEL would do, with the added benefit of more detailed userpages, extended leaderboards, free access to anyone without an anonymous or registered account, and more detailed server statistics. Specifically, solo leaderboards would be extended from the top 100 to the top 1000, the TETRA LEAGUE player leaderboards would be extended to every ranked player, and the XP leaderboards would be extended to every player above level 100. Furthermore, both "player leaderboards" could now be filtered by specific countries as well.
A similar "search bar" to the one found in the ingame TETRA CHANNEL is present in all pages on this site as well. This search bar will only accept exact usernames, and when utilized, takes the user to the requested userpage. A userpage is far more detailed than their ingame player card counterpart, and includes highly detailed information about a given user's 40 Lines and Blitz personal bests, as well as links to their top ten replays in both solo modes, and their last ten most recent submitted replays. Additionally, TETRA LEAGUE statistics and the last ten Tetra Leage replays can be found here, coupled with simple Zen mode counters signifying what score and level a user has in that mode.
An extended "Tetra News" section would be included with this site as well. Normally, from the front page, the Tetra News section mirrors that of the Tetra News from the ingame TETRA CHANNEL. However, below all of the "global news" lies a button labeled "VIEW ALL". This link will take you to a dedicated Tetra News section of the site, where a news ticket is created whenever any registered user gets a new personal best, ranks up to a "personal best rank", meaning this is the first time they've ever been in that given rank; and achieving any of TETR.IO's many badges. This page will only fetch the last 100 news events, and updates on its own whenever new news events occer. These news events are known as "Local News", and show up on the newsholder's userpage long after they expire from this global local news section.
You can always fetch a list of various extremely up-to-date stats from the TETRA CHANNEL's main page, including, but not limited to: the exact amount of registered players split up into three categories, global time spent playing TETR.IO across all games, how many of those games have been played and completed, and miscellaneous stats such as pieces placed and how many keypresses that took.
On the 3rd of November, 2020, TETR.IO reached the milestone of half a million players. This milestone was celebrated with a "triple XP week" which, as the name sort of implies, tripled the XP players gained for the time the celebration ran.
TETR.IO hit a total of one million players on the 9th of February, 2021. This milestone was celebrated by, once again, temporarily multiplying the XP amounts players gained for the week of the celebration. This time, XP would be quintupled for the first day, then tripled for the rest of the week.
Later on, TETR.IO would reach a total of two million users on the 31st of May, 2021. As well as the same XP multiplication as last time, 500% for one day, then 300% for the rest of the week, users would also be treated to a 25% off discount on TETR.IO Supporter for the entire week. This discount stacked with the regular discounts for buying gifts, or buying in bulk.
Continuing the streak, TETR.IO would celebrate the 3 million player mark on the 17th of September, 2021. This time around, the XP multiplication hit 300%, and TETR.IO Supporter was 30% off instead of 25%. These discounts and boosts would expire just 3 days later, this time around.
And, more recently, TETR.IO's playerbase would make the mark of 4 million players on the 8th of December, 2021. Staying true to form from the previous milestone, players were treated to 400% XP generation, as well as a 25% TETR.IO Supporter discount for only one day.
Professional Concerns: The Removal of Passthrough
Many players in the community hold a very low opinion on TETR.IO's passthrough and, to a lesser degree, Multiplier mechanics. Previously, these mechanics would complement each other in creating unfair situations for both players; so much so, a large community-led discussion regarding the removal of the passthrough mechanic was held due to its prevalence in deciding ranked games. While concepts regarding passthrough's removal was always tossed about with nearly any server related to TETR.IO, the discussion, which led to passthrough's official removal, began in an official capacity on the 28th of September, 2021, in a Discord thread in the official TETR.IO server. Players were informed and instructed to leave feedback about a new, experimental toggle for passthrough, through the #news channel and ingame patchnotes alongside the 6.1.0 update. Thanks to this official push for opinions, the "Passthrough Removal" thread quickly became the second most active and popular one in TETR.IO's thread list with approximately 146 members today, leading only behind the "Official Character System Thread", which has about 195 users in it.
Please only vote if you've actually played w/ passthrough disabled. I won't be looking so much at the raw vote counts, but rather at the reasons given. Please be sure to fill them out. Thank you for voting!
While discussion in the thread progressed semi-smoothly, it was necessary to attain an overview of players for and against the change. To solve this issue, osk would set up a site known as https://passthrough.osk.sh/. While the form is closed today, during the submission period, members were asked to fill out only 3 forms.
- Are you for or against the removal of passthrough?
- What is your TR? (if any)
- "Please explain in detail why you have voted to keep/remove passthrough. This is the most important field!"
These questions would be answered by the community, amounting to a total of 649 entries, with duplicate or spam entries filtered out. Of those entries, 243 users voted to keep passthrough, and 406 users voted to remove it.
After reading all 649 responses, I've decided to remove passthrough from TETRA LEAGUE and QUICK PLAY, and disable it by default in all custom games.
The main reasoning here being that passthrough generally makes defending harder in an already high-damage game, and most importantly, is far too unpredictable (even pure RNG would be more predictable).
While passthrough has been "removed", it is very important to note that passthrough is still possible, due to networking delays.
Like most of the internet, on April 1st each year, TETR.IO takes part in the April Fools' Day festivities usually by changing the system Quick Play room's ruleset to one that is both unconventional and impossible to recreate for the normal user, and by changing the so-called "action text" that appears when the player clears lines, T-Spins, All Clears, and Back-To-Back moves.
April Fools' 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 this year's April Fools' was one singular unclearable block, located on the first row in the third column, leaving that row unclearable. Since garbage is added into the board from the bottom, once players covered a column on row 1 with a regular piece, garbage which has entered that row would become unclearable by extension. Furthermore, the garbage multiplier was set to a staggering 9999x, garbage margin time started instantly, the "ALLOWED SPINS" setting permitted "STUPID SPINS", and your next queue was reduced from five pieces to four. The "GARBAGE CAP" setting was set to a limit of 1 garbage line allowed to enter the field per non-line clearing piece placed, so matches wouldn't end the instant you received that aforementioned multiplied 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|
|x-SPIN||LARGE x-SPEEN[fools note 1]|
|MINI T-SPIN||TINY T-SPEEN[fools note 2]|
|ALL CLEAR||(unknown)[fools note 3]|
|BACK TO BACK( x)||MANY TIMES( x)[fools note 4]|
|COMBO[fools note 5]||(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 reply with the vice-versa action.
- Where "x" is the piece counted for the spin.
- The T tetromino will always be the piece to trigger this text. You cannot achieve a mini spin with any other piece, as TETR.IO uses "Immobile" spin detection for every non-T piece.
- Despite it being impossible to All Clear in Quick Play, it was possible to trigger this text in other modes. Considering nobody freaked out about this particular action text, it's highly probable that it simply wasn't changed.
- Where is equal to the amount of consecutive Back-To-Back line clears. "BACK TO BACK x1" is never shown, as a simple "BACK TO BACK" is prefered over the former.
- Where correlates to the current combo value.
April Fools' 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 normal allspin[fools note 1], however instead of using guideline tetrominos, all players were served the same seven randomly generated pieces known as "fractured" pieces. These pieces could be anywhere from one mino to sixteen minos large. Each fractured piece correlated to one of the regular seven guideline tetrominos both visually in the next/hold queue[fools note 2] and in the "x-WIST"[fools note 3] action text. Due to the randomly generated nature of these pieces, the Super Rotation System kickset was not a good fit for this mode. Hence, the dynamic "ASC" kicktable, originally created for winterNebs' Ascension, made a good fit for the mode. The kick table might not have been the only bit of inspiration taken from that site for this mode. Ascension's "Mutation" mode generates very similar pieces on later mutation levels. Fortunately, the ASC kick table was already implemented into TETR.IO as of update 0.7.2-pre0 released the year prior, however, despite the groundwork already existing for the kick table, the ASC kick table does not define 180 kicks to be used, so custom modifications adding mentioned 180 kicks were made to the ASC kick table at the time for this special mode. 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.
The action text switches this time around took a more simplistic approach to displaying how many lines a single piece cleared:
|Original action text||Replaced action text|
|PENTA, HEXA, HEPTA, etc||SINGLE x[fools note 4]|
|KAGARIS[fools note 5]||KAGARIN IS CUTE|
|x-SPIN||x-WIST[fools note 6]|
|MINI T-SPIN||MINI T-WIST[fools note 7]|
|BTB x||CHAIN x[fools note 8]|
|COMBO[fools note 9]||(unchanged)|
The "T-WIST" text is likely a reference to GlitchyPSI's YouTube video titled "A casual day with a twist.". This only seems likely since GlitchyPSI and osk are on good relations, as GlitchyPSI was one of the first to get the "contributor" role on the TETR.IO Discord server. 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 there's a higher chance it simply references the name of the Back-To-Back Chaining mechanic.
The TETR.IO Discord server did their 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 the date hit April the 1st for the CEST time zone, the following announcement was made in #news parallel to the update that changed the Quick Play ruleset:
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 would 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.
- 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
- Since TETR.IO Allspin already operated under "Immobile" detection, it adapted easily to the newly generated pieces.
- Fractured pieces were not reflected in the next/queue, however the blockout warning signifying the next piece's spawn position did mirror its fractured counterpart. Each fractured piece were constructed in a grid the size of their "normal" counterparts, which means that the corresponding O piece had to be restricted to a 2x2 grid, the corresponding I piece in a 4x4, and the rest in a 3x3 grid
- Where "x" is the piece counted for the spin
- Where is equal to the amount of lines cleared with a single line clear. More information in the trivia section.
- This is the line clear achieved when 21-40 rows are cleared at once. More information at the trivia section.
- Where "x" is the piece counted for the spin.
- The T tetromino will always be the piece to trigger this text. You cannot achieve a mini spin with any other piece, as TETR.IO uses "Immobile" spin detection for every non-T piece.
- Where is equal to the amount of consecutive Back-To-Back line clears.
- Where correlates to the current combo value.
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 on the TETR.IO Discord server
Following the trends of other services, TETR.IO also partakes in seasonal redecorating. So far, we can expect a full changeup of vanilla backgrounds, boards, accent colors, and skins with the addition of snowy particles, as we saw during the weeks of December 19, 2021 - January 4th, 2022. This slight reskin was also responsible for some interesting developments as far as the modularity of TETR.IO customization is concerned, being the first deployment of skin/ghost mix-n-matching and introducing entirely new textures to the internal "board.png" file, doubling its size, which was later ditched when the update was reverted.
You could not opt out of these customizations while they were active, although you could of course change the background to a custom background of your choosing. As of now, there is no way to access these customizations again, post-holidays.
TETR.IO staff members are users responsible for moderation and general upkeep of the game and its community. Their main responsibilities include reviewing reports, answering support tickets, and moderating the Discord server.
Staff members have access to the admin panel, which is the main interface for moderation actions. They also have access to the support ticket system, and a role in the TETR.IO Discord server which grants them moderation permissions, as well as access to staff-only Discord channels.
Moderators are recognised by their blue name in game and on Discord. As well as having the power to access most features of the admin panel, they also have all Supporter and Verified perks, a handful of staff-only emotes (including a large version of "ultreme"), and the ability to take ownership of any in-game lobby.
At least five orginal Moderator accounts exist, presumably appointed during the Indev phase.[note 4]
Furthermore, two additional moderators were appointed, or at least created, at some point after the end of the Indev phase.[note 5]
In May 2021, a further two moderators were appointed.
Then, two more moderators were appointed in August 2021.
Administrators (presumably) have full control over the game, which includes all moderation tools, as well as the ability to make permanent changes to the game itself via updates. They can easily be spotted in game and on Discord thanks to their signature green usernames.
TETR.IO began its life in the INDEV stage on the 19th of February, 2019. This phase would have extremely closed testing, limited to only osk and their personal friends. Less than a year later, TETR.IO would enter the INFDEV stage on January 31, 2020, when access to the game was opened for testers on a per request basis. During the Infdev release, players were required to represent their IP address to osk via Discord DMs or E-Mails in order to test this version. A month and a half later, the game entered the public Alpha stage on March 22, 2020. This time, all players are free to create/log in to their accounts and play the game.
On May 22, 2020, a desktop client of TETR.IO was released. Aside from being able to open the game without a web browser, this also allows users to play single-player modes offline.
- A player's "level badge" evolves into different shapes and colors every ten levels, starting from level 1. Furthermore, levels supposedly cap at level 5000, however, as no TETR.IO player has reached this level, this fact remains a myth.
- If the "First To" value is higher than 2 in any given multiplayer Battle Royale with less than eight players, the scoreboard at the top of the screen will match the colors of the seven Tetrominos, displaying each player and their current amount of wins.
- If the user uses command "/kagari" in room chat, they will be greeted with a system message, only the user invoking the command can see, which contains "CMD: :kagari:".
- The "WASD" control scheme, one of three choices in the controls config, is a direct mirror of osk's personal controls; the same controls they thought up on the spot in Tetris Friends since they didn't quite like the default controls.
- Some aspects of TETR.IO's design are loosely based off the Bejeweled series. An example of this inspiration involves the Zen mode level up animation, which reportedly comes from Bejeweled 2's similarly named Zen mode. You can even draw comparisions down to the color schemes of the Solo mode selection screen to Bejeweled Twist; a game that also has a red "Blitz", turquoise "Zen", and yellow "Challenge"+"Classic" buttons.
- As of version 6.0.1, achieving a higher TETR.IO Supporter tier will cause a player's name to show in a brighter shade of orange in game, assuming they have Supporter themself. Tier 1 is achieved after purchasing Supporter or receiving a gift, Tier 2 (★) is currently achieved after lifetime supporter contributions reach €20, Tier 3 (★★) is €80 and Tier 4 (★★★) is €250.
- It is possible to clear more than five lines with one piece, thanks to the Zen mode update. In it, code was activated which made it possible to load what's known as a "map field", through the use of some devtool hacking, or with the aid of a third party mod. At first, clearing more than four lines with one piece would softlock the game as it tried to find action text for an action that wasn't defined, however, starting with the 4.1.0 update released on the 16th of July, 2020, that issue was removed. In return, osk added in the following action text for when players clear more than four lines:
|Lines cleared||Action text|
- Despite these normally impossible actions being recognized through action text, these line clears do not send any lines[note 6] or count for any score. If you end up testing this yourself, ensure there are no all clear bonuses in play.
- An easter egg lurks in the social panel. If you use the search bar to attempt to find a user who is not your friend, you will be greeted with a message containing "Couldn't find anyone like that." in place of search results. If you then search for "anyone like that" you'll be greeted with a different message. This loop continues for quite a bit:
|Search query||Ingame response|
|anyone like that||Couldn't find anyone with that name.|
|anyone with that name||Couldn't find that person.|
|that person||Couldn't find the specified user.|
|the specified user||Couldn't find anyone in your friends list with that name.|
|anyone in your friends list with that name||Couldn't find who you are looking for.|
|who you are looking for||Couldn't find any user in your friends list who matches the specified search term.|
|any user in your friends list who matches the specified search term||...|
- At this point, the error icon will switch from an innocent depection of Kagari to a more judgemental Kagari. Searching for "..." will result in the regular error message, "Couldn't find anyone like that."
- Specifically, TETR.IO officially supports Chrome 67≤, Firefox 56≤, Edge 79≤, and Opera 66≤
- Specifically Desktop V5 and up is supported. If one launches Desktop V4, for instance, they will be met with a screen informing them the current Desktop client version is unsupported alongside links to update, and the game will refuse to load.
- Much smaller patch update. There weren't even patchnotes for this one, so consider the citation the ingame F8 menu.
- This is an unofficial list which may be incomplete!
- These accounts were created after the account creation time started being recorded, as opposed to the original five which show as "here since the beginning", implying they were created after the Indev phase.
- Confirmed through ZEN mode's "sendback" garbage option.
- "6.0.1 Update Log". TETR.IO Patchnotes. March 7th, 2021. Retrieved .
- "TETR.IO Forty-Four Fact Frenzy!". osk blog. December 17th, 2019. Retrieved .Fact 7: Spiced up Garbage
- "2.3.2 Update Log". TETR.IO Patchnotes. June 2nd, 2020. Retrieved .
- "4.2.0 Update Log". TETR.IO Patchnotes. July 30, 2020. Retrieved .
- "6.1.2 Update Log". TETR.IO Patchnotes. October 18, 2021. Retrieved .
- "0.6.0-pre0 Update Log". TETR.IO Patchnotes. June 2, 2020. Retrieved . "➔ Added 180 spins."
- "2.0.0 Update Log". TETR.IO Patchnotes. June 2, 2020. Retrieved . "➔ Added the rotation system SRS-X." "➔ This is SRS, except with Nullpomino/Heboris-style 180s."
- "5.0.0 Update Log". TETR.IO Patchnotes. September 28, 2020. Retrieved . "➔ Added SRS+!"
- "5.0.0 Update Log". TETR.IO Patchnotes. September 2, 2020. Retrieved . "➔ Introducing the standalone TETRA CHANNEL SITE!"
- "Thank you to everyone who played TETR.IO this year! 2021 was an amazing year, and 2022 looks to be very exciting!". Twitter. January 1st, 2022. Retrieved .
- "TETR.IO has just reached 500,000 TOTAL PLAYERS!!!". Twitter. November 3rd, 2020. Retrieved .
- "ONE MILLION". osk blog. February 9th, 2021. Retrieved .
- "TETR.IO has just reached 1,000,000 players!!!". Twitter. February 9th, 2021. Retrieved .
- "TETR.IO just reached TWO MILLION players, including anonymous, not even 4 months after hitting 1 million!". Twitter. May 31st, 2021. Retrieved .
- "TETR.IO just reached 3,000,000 total players!!! 735K of those are registered!". Twitter. September 17th, 2021. Retrieved .
- "TETR.IO just reached 4 million players! 900K of those are registered!". Twitter. December 8th, 2021. Retrieved .
- "6.1.0 Update Log". TETR.IO Patchnotes. September 28, 2021. Retrieved .
- "Vote for the change of the default passthrough mode and removal of passthrough from TETRA LEAGUE". osk "passthrough" subdomain. October 18, 2021. Archived from the original on October 8, 2021. Retrieved .
- "this is what was committed, but the garbagecapmax should also be 1, and idk, garbage multiplier was proabbly smth like 99999". Discord. May 8, 2021. Retrieved .  -osk on the TETR.IO Discord server
- "0.7.2-pre0 Update Log". TETR.IO Patchnotes. June 2, 2020. Retrieved .
- "180° spin kicks in ASC". Github. August 26, 2020. Retrieved .
- "The handling feels slippery, but my settings are the same as on JSTRIS". TETR.IO Statistics by Tenchi. Retrieved .
- "The Beginning". TETR.IO Patchnotes. June 2, 2020. Retrieved .
- "TETR.IO is now in INFDEV!". osk blog. January 31, 2020. Archived from the original on February 8, 2020. Retrieved February 8, 2020. "Want to try out TETR.IO? Contact me with your IP and why you would like to try out TETR.IO, and I'll add you to the whitelist!"
- "TETR.IO PUBLIC ALPHA RELEASED!". osk blog. March 22, 2020. Retrieved .
- "3.0.0 Update Log". TETR.IO Patchnotes. June 2, 2020. Retrieved . "➔ THE OFFICIAL TETR.IO DESKTOP CLIENT IS HERE!"
- "How do you import a custom map?". TETR.IO Statistics by Tenchi. Retrieved .
- "4.1.0 Update Log". TETR.IO Patchnotes. July 16, 2020. Retrieved .