The game can also cause a repetitive stress symptom in that the brain will involuntarily picture tetris combinations even when the player is not playing the game (the Tetris effect; for citations see the references in the article Tetris Effect), although this can occur with any computer game or situation showcasing repeated images or scenarios, such as a jigsaw puzzle.
Tetris
A random sequence of tetrominoes (sometimes called "tetrads" in older versions)—shapes composed of four square blocks each—fall down the playing field (a rectangular vertical shaft, called the "well" or "matrix"). The object of the game is to manipulate these tetrominoes, by moving each one sideways and rotating it by 90 degree units, with the aim of creating a horizontal line of blocks without gaps. When such a line is created, it disappears, and any block above the deleted line will fall. As the game progresses, the tetrominoes fall faster, and the game ends when the stack of tetrominoes reaches the top of the playing field and no new tetrominoes are able to enter.