List of TGM series bugs

This is a list of TGM series bugs.

The Grand Master

Bugs for Tetris The Grand Master.

Gameplay

• Big Mode pieces will be truncated into half-rows if they are placed in row 22, since the playfield only has 21 rows.
• For the first piece of the game, you cannot charge DAS during ARE. Note that if you charged DAS on the previous credit, and keep holding that direction, then you will have DAS on the first piece.
• If you charge DAS long enough, the charge timer will roll over from 255 to 0 and you can lose the DAS charge without ever releasing the directional input. However, it's very difficult to have this actually occur.
• Holding down both left and right at the same time charges DAS at double speed. This is not possible when using the intended arcade stick input method.
• The game lags for one frame whenever a section boundary is crossed.
• Unlike other games in the series, it is posible to rotate clockwise and counter-clockwise in the same frame. While the net piece orientation is unchanged, the piece will wallkick if possible effectively moving 1 column. This means that it's possible to move 2 columns in 1 frame.

Cosmetic

• If you mash buttons during the attract mode, you can glitch out the demo replay and cause it to top out.
• If you earn enough points to take you straight from S8 to GM (with GM conditions fulfilled), then the game will not play the "grade up" sound or have any graphical effects. The grade graphic will simply and silently update.
• The screen area of the game playfield is not perfectly divisible by 10, so some columns/rows have spaces that are slightly rectangular rather than square.
• The font used to display grade requirements, score, and levels has a maximum 32 characters onscreen at a time. It is possible to exceed this number, after which additional characters will not be rendered. This will hide some or all of player 2's level counter, making it almost impossible to judge level stop boundaries.
• If you press start to begin a new run on the same frame that the game was going to transition to attract mode on, the new run starts immediately without returning to the title screen. This is normally only possible when starting a credit on the other player while a run is in progress.
• If you win a round of versus with a bravo, the text "Win" and "BRAVO !!" will be rendered on top of each other making them difficult to read.
• If a run goes on for over an hour, the timer will roll over from 59 minutes to 0. However, the run still ranks correctly on the leaderboard, and this would never happen without deliberate stalling strategies.

The Absolute PLUS

Bugs for Tetris The Absolute The Grand Master 2 PLUS.

Gameplay

• Big Mode pieces will be truncated into half-rows if they are placed in row 22, since the playfield only has 21 rows.
• Grade points for combos have an off-by-one error in the table lookup, causing Tetrises to be nerfed and other line clears to be buffed. This was corrected in TGM3.
• Input drops in Doubles during lock frames. Even a DAS movement will pause for a frame mid-movement. This phenomenon has port priority. When player 1 locks, player 2 loses input that same frame. When player 2 locks, player 1 loses input the next frame.
• DAS charging does not stop after hitting the threshold. After 256 frames of charging it will rollover. If the rollover happens during active time, you can see a piece stop and recharge mid-movement.
• Line clears do not register in row 21. (Mainly can happen after receiving garbage in Versus and IRS'ing into a line clear.)
• Mirror Block does not mirror row 21.
• Mirror Block ends immediately without animation if the player does a bravo.
• Piece snipes from attack items in versus that occur on the last frame a piece is active will, after much delay, snipe the next piece immediately after spawning.
• Exchange Field fails if the attacker is receiving 180 Field. Despite the animation of Exchange Field they will still get their original stack 180'd.
• Due to the more sophisticated RNG function only running during attract mode, runs started right after another have a very limited selection of possible piece sequences (around 2100 different seeds). This makes it reasonable for the exact same sequence to be rolled twice in a row.

Cosmetic

• The framerate is ~61.68 Hz, but the in-game timer assumes a framerate of 60 fps. Other games running on this hardware run much closer to 60 Hz.
• The music will occasionally get stuck on a note. As the music continues it will eventually fix itself.
• Tetrises mid-combos will fail to play any crowd sound effect. Non-Tetrises play a cheering sound similar to TGM1. For Tetrises TGM1 would play a crowd gasping sound. Notably, the gasping sound can still be heard in the TAP sound test as effect #26.
• M ranks will often report an incorrect "grandmaster ranking" or "today's ranking" in the results screen. This is due to the M grade uniquely being awarded at the moment you top out in the credits, which causes the results screen to miscalculate the score as if it were a green line S9 grade. This bug does not affect the actual saving to the leaderboards, only the displays on the results screen. However, if the bug causes the M to be perceived as out of rank on both the Grandmaster Ranking and Today's Ranking, the results screen will not come up at all and the M will not be saved. This can be avoided by holding down ABC at the end of the run to bring up the verification code initials entry screen (originally designed for the official Arika online leaderboard). Going to this screen will force the regular results screen to come up, causing the run to be saved properly.
• Secret Grade is detected in Versus Mode, on the last game of the credit.
• Sprite overflow is possible, especially if 2 players are playing Item Mode. Sprites beyond the limit will not be correctly rendered.
• Doubles Mode end of credit behavior is strange. Under poorly understood conditions, it is possible to softlock the game or for the game to request the players to enter their initials twice. This can also cause the same run to register to the leaderboard twice.
• Border line in row 21 may not display correctly, under some circumstances. The border line function reads data outside of the playfield array.
• Games ending during a line clear behave strangely, with the active piece remaining fully intact.
• Some backgrounds clearly intended to have a solid black color, however the game has left a grey color as the backdrop color making it look wrong.

Terror-Instinct

Bugs for Tetris The Grand Master 3 Terror-Instinct.

Gameplay

• Big Mode pieces will be truncated into half-rows if they are placed in row 22, since the playfield only has 21 rows.
• Killspeed that kicks in after 15 minutes of play does not invalidate the run for high scores. In particular, this means you can cheese otherwise-impossible section time records. TAP has a killspeed but does not have this bug.
• World Rule limits the amount of times lock delay can be reset, preventing infinite stalling. However, an oversight is that some kicks move a piece upwards without needing to touch the ground. In this way, you can stall forever (well, until the killspeed kicks in) using only a single piece.
• Easy Mode has a too-short lookup table for determining the credit roll combo bonus. The data found when overflowing the table is all zeros. The end result is that a combo of 9 or 10 doubles will have a x1.0 combo bonus instead of an 8 combo's x2.9 bonus.
• World Rule's I-piece wallkicks do not match the the Tetris Guideline.
• Due to the Taito Type X being a Windows PC based platform, the game often lags significantly on the first particle effect (line clear, firework, etc.) after power-on.
• When the randomizer has re-rolled (it tried to pick a piece in the history), and chooses the least recently dealt piece, the 35-piece pool is not updated. Normally the newly least recently dealt piece should be swapped with the chosen piece in the pool. This only happens if the game has not yet dealt you 1 of every piece type (excluding the first piece and including the rerolled droughted piece).
• The maximum gravity, which in terms of game design is functionally infinite, is literally 20G. Using World rules, it is possible to kick a piece high enough to need to fall more than 20 rows. In these cases, you can observe that a piece will only fall 20 rows. Also, this reveals that Shirase 0-100 technically has TLS active.
• Hard drop appears to be programmed using similar 20G logic, immediately locking a piece after processing 20G gravity. This means that when a piece is more than 20 rows high, it will lock in the air after falling 20 rows.
• Versus Mode item meter charging has a bug with Hold. IHS will entirely prevent the meter from charging, whereas active time Hold will increment the meter by 1 piece. It's unclear if the intended behavior is to nerf Hold (but failing to implement this for active time), or else if active time Hold was increasing the meter twice and IHS got nerfed in fixing that bug.
• The walls of the playfield are 26 rows tall, and there's no ceiling. In World Rule Big Mode, it's possible to use kicks to move a piece over the top of the stack and out of bounds.

Cosmetic

• Piece previews in Shirase 1000+ do not follow the same "flush with bottom" alignment of normal play. In particular the I piece is 1 row higher and may be difficult to see.
• Leaderboard times are 0.10 seconds faster than in-game times. TGM1 and TAP both stop their time the first frame that a line clear is visible. The TGM3 leaderboard does it 1 frame before the line clear is visible. The in-game times stops after the line clear animation finishes. Note that for some reason Easy Mode leaderboard times are not 0.10 seconds faster, they match the in-game time.
• Rotated screen frames are possible if you win a versus match while in the middle of the frame spin animation. It will stay rotated, obscuring the playfield, until the next credit re-initializes things.
• Classic/Word indicators in the highscore list can have their highlighting messed up (active ruleset will be dark, other ruleset will be bright) by pressing a diagonal input to change the ruleset (up/down) and leaderboard (left/right) in the same frame.