Wall kick

A wall kick happens when a player rotates a piece when no space exists in the squares where that tetromino would normally occupy after the rotation. To compensate, the game sets a certain number of alternative spaces for the tetromino to look. Wall kicks started appearing in games because after a piece would be backed up against the wall, it would awkwardly be unable to rotate until first moving back. Notable rotation systems that include wall kick include the following:
 * The rotation systems of the domino based games Dr. Mario, Puyo Pop, and Super Puzzle Fighter II.
 * The rotation system of Tetris DX, which allows wall climbing
 * The rotation system of The New Tetris, considered a predecessor to SRS
 * SRS, the Super Rotation System used by games that follow the Tetris Guideline
 * TGM rotation

Koryan as well as Jagorochi researched the SRS system thoroughly and made diagrams of how SRS finds wallkicks.

The complete system for a number of Tetris games exists in wktables.c within open-source Lockjaw.