I-Spins in SRS

Different rotation systems that approximate SRS apply different wall kicks and floor kicks when the player twists the I tetromino.

Official SRS[]

Tetris Worlds, Tetris DS and Tetris The Grand Master Ace are based on the Tetris Guideline, including SRS. They have the following behavior:

Rotated left

Soft dropped

Rotated right

Doing it the other way would make it kick up:

Rotated right

Soft dropped

Rotated right

But the wall kicks are not symmetric, as Tetris Worlds, Tetris Deluxe, Tetris DS and Tetris The Grand Master Ace prefer to kick up rather than down when rotating left...

Rotated right

Soft dropped

Rotated left

...unless there is an extra block to force a kick down.

Rotated right

Soft dropped

Rotated left

The following can be performed instead. This is a well-known cheat in Tetris DS.

Rotated left

Moved right

Soft dropped

Rotated left

Tetris Advance[]

Minna no Soft Series: Tetris Advance, while implementing SRS, included several bugs including the lack of some wall kicks.

Rotated left

Soft dropped, can't rotate right

Lockjaw[]

In Lockjaw, both left and right prefer to kick down rather than up when rotating:

Rotated right

Soft dropped

Rotated left

However, Lockjaw has an extremely glitchy kick from the second to the first or third orientation, making it unusable.

Theoretical SRS variations[]

The inconsistencies in SRS I rotation are caused by whether the 2 side kick goes before or after the 1 side kick, and whether the {±2,±1,} kick comes before or after the {±1,±2,} kick. Turns out, there are:

65536 such variations with no restrictions
256 symmetric variations (official SRS is not symmetric)
256 reversible variations
24 variations expressible as an offset table (official SRS is an offset table)
16 symmetric reversible variations
4 symmetric offset table variations

Offset table variations[]

The 24 offset table variations are a combination of the six side kick variations and four endpoint kick variations:

Side kick variations:

prioritize 1-kicks (used in tetrisimplementation)
prioritize 2-kicks
prioritize preserving left endpoint laterally (used in official SRS)
prioritize preserving right endpoint laterally
prioritize preserving left bounding edge
prioritize preserving right bounding edge

Endpoint kick variations:

prioritize 1,2,-kicks
prioritize 2,1,-kicks (used in tetrisimplementation)
prioritize preserving left endpoint (used in official SRS)
prioritize preserving right endpoint

tetrisimplementation uses a symmetric offset table system that does the 1 side kicks before 2 side kicks, and {±2,±1,} kicks before {±1,±2,} kicks. Therefore, B and D kick down, but A and C kick up.

Tetris Best/Tetris Return[]

Similar to SRS, the rotation systems used in Tetris Best (TBRS) and Tetris Return (TRRS) also allow this I-spin. Both left and right prefer to kick down, so the problem is solved.
Also, it is possible to do an I-spin tetris. It works from both directions.

old Tetris Best: