video game created by Russian designer Alexey Pajitnov in 1985 that allows players to rotate falling blocks strategically to clear levels. Pajitnov claimed he created the name of the game by combining the Greek prefix tetra, which refers to the four squares contained in each block, with the word tennis.

Tetris has been released for virtually every computer and electronic gaming (electronic game) system, and it is often revered as a classic. Though numerous sequels have been spawned, Tetris games almost always have the same play mechanics: differently shaped blocks drop at varying speeds, and, as the blocks descend, the player must rotate and arrange them to create an uninterrupted horizontal row on the screen. When the player forms one or more solid rows, the completed rows disappear. The goal of the game is to prevent the blocks from stacking up to the top of the screen for as long as possible. Subsequent versions of the game included different modes of play and unique twists, but the overall game play usually mirrored the original Tetris quite closely.

The Tetris franchise endured years of litigation regarding licensing rights, but this did not stop the game from being featured on Nintendo's Game Boy, where it rose to stardom. Later versions, however, incited anger among Tetris purists, who objected to an “infinite spin” mechanic that afforded the player additional time to place a block by rotating the block rapidly as it descended.