Arika Rotation System
TGM rotation is a game play mechanic used in Tetris The Grand Master and other Arika tetromino games, derived from Sega rotation. It is often refered to as ARS (Arika Rotation System), even though some people believe that this name is misleading.
Games using TGM rotation generally use IRS, fast DAS, lock delay, and firm drop, and tetrominoes start out with the topmost block on the top row (generally row 20). The "ARS" and "ARS2" modes of Tetris The Grand Master Ace use a hybrid of TGM rules and Guideline rules.
Basic rotation
TGM's basic rotations inherits most of its properties from Sega rotation, which was used in most previous Japanese arcade Tetris games. Some defining characteristics include:
- Having 2 (as opposed to 4) rotation states for S, Z, and I tetrominoes.
- Keeping tetrominoes at an even level while rotating to always allow rotation when the tetromino is on a flat surface (except for the I tetromino - see exceptions below).
- Pointing the initial stance of the T, L, and J tetrominoes downward.
Wall kicks
TGM pioneered the use of wall kicks, with simple but effective kick rules. These rules were unchanged until TGM3, remaining constant across TGM, TA, TAP, and Sakura Tetris. Up to 3 locations are tried, in this order, before rotation will fail:
- Basic rotation
- 1 space right of basic rotation
- 1 space left of basic rotation
In addition to these rules, there are some extra exceptions where certain wall kicks are not allowed:
- The I tetromino will never kick.
- L, J, and T tetrominoes will not rotate in the situations illustrated below if the
marked block is occupied.
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- However, L tetrominoes will rotate clockwise and J tetrominoes counterclockwise in the situations illustrated below if both the marked blocks are occupied.
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New wall kicks in TGM3
I tetromino's wall kicks
In TGM3, the I tetromino can kick walls. There are 3 different types of wall kicks.
Try to rotate |
Basic rotation fails |
Kick 1 space right | |||
Try to rotate |
Basic rotation fails |
Kick 2 space right | |||
Try to rotate |
Basic rotation fails |
Kick left |
I tetromino's floor kicks
The I tetromino can kick the floor.
Notes:
- Like hold piece, floor kick can be performed only once per tetromino.
- The tetromino cannot kick the floor in mid-air.
Fail |
OK |
OK |
There are 2 different types of floor kicks.
Try to rotate |
Basic rotation fails |
Kick 1 space up | |||
Try to rotate |
Basic rotation fails |
Kick 2 space up |
T tetromino's floor kicks
The T tetromino can escape from a hollow.
Notes:
- This action can be performed only once per tetromino.
Try to rotate |
Basic rotation fails |
Kick up |
Right side bias
In TGM's rotation system, the Tetrominoes rotate on only one axis resulting in asymmetrical rotations. In this example, the I piece can't rotate on the left side of the stack;
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A situation which would work on the right side.
Notice the I has 1 rotation axis;
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I piece's rotation axis
This case does not apply to the T tetromino, as it rotates on its center;
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T rotation axis
Mihara's conspiracy
Due to the right side bias with wall kicks, doing this move with a J when there is an empty hole right of the block that the J is caught on will lead to a hole.
L works:
Firm drop |
Rotate left |
Kicks to here |
J does not...
Firm drop |
Rotate right |
Kicks to here |
...unless there is another block to force a kick to the left.
Firm drop |
Rotate right |
This fails too |
Kicks to here |
It can however be used to the player's advantage by it being used to jump over spikes.
ACE-ARS and ARS2
ARS was featured as a Xbox live download for ACE. Ace's rotation is a hybrid of SRS and ARS. Ace features guideline colors and allows 128 rotations and 128 movements (Rather than true infinity). ACE features the ability to floor kick with any block, but still retains the wall kick rather than floor kick behavior from the original TGM rotation. Normal ARS features Sonic Lock (locking hard drop) and non-locking soft drop. ARS2 had Firm Drop (non-locking hard drop) and soft drop (locking).
To-Do
- describe ACE's ARS and ARS2
- describe "Mihara's conspiracy" (Complete)
- mention right bias (Complete)
- add more visual aids?