Tetris is a puzzle computer game, released on an extremely large spectrum of platforms. The game is available for every video game console and computer operating system, as well as on devices such as graphing calculators, mobile phones, portable media players, PDAs and it is composed from a sequence of tetrads (tetramineos) of four square blocks each-fall down the playing field.

These tetrads can be manipulated 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 the blocks above fall. As the game progresses, the tetrads fall faster and it ends when the player "tops out", and when the stack of tetrominoes reaches the top of the playing field and no new tetraminoes are able to enter.

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