Tetris is a tile-matching video game created by Russian software engineer Alexey Pajitnov in 1984. It has been published by several companies, most prominently during a dispute over the appropriation of the rights in the late 1980s.

Tetris is primarily composed of a field of play in which pieces of different geometric forms, called “tetriminos”, descend from the top of the field. During this descent, the player can move the pieces laterally and rotate them until they touch the bottom of the field or land on a piece that had been placed before it. The player can neither slow down the falling pieces nor stop them, but can accelerate them in most versions. The objective of the game is to use the pieces to create as many horizontal lines of blocks as possible. When a line is completed, it disappears, and the blocks placed above fall one rank. Completing lines grants points, and accumulating a certain number of points moves the player up a level, which increases the number of points granted per completed line.