Tetris was created by Alexey Pajitnov, a Soviet computer scientist working at the Dorodnitsyn Computing Centre of the Soviet Academy of Sciences in Moscow, on June 6, 1984. Inspired by pentominoes (geometric puzzle pieces made of five squares), Pajitnov simplified the concept to tetrominoes (four squares) to make the pieces more manageable. He programmed the first version on an Elektronika 60 computer, and the game spread virally through Moscow's academic computing community before eventually being licensed internationally through a complex web of deals involving the Soviet government, multiple Western companies, and what became one of the most contentious intellectual property disputes in gaming history. The game achieved global fame when it was bundled with Nintendo's Game Boy in 1989, selling over 35 million copies and establishing both the Game Boy and Tetris as cultural icons.

From a computational complexity standpoint, Tetris is provably NP-complete. In 2002, Erik Demaine, Susan Hohenberger, and David Liben-Nowell proved that determining whether a given sequence of Tetris pieces can be played to clear a specified number of rows or to survive for a specified number of pieces is NP-complete. This means that optimal Tetris play, deciding the best placement for each piece given the future piece sequence, is computationally intractable in the general case. Even more surprisingly, Ron Breukelaar and colleagues showed in 2004 that Tetris remains NP-complete even when the player knows the entire piece sequence in advance. These results explain why Tetris feels so challenging: perfect play requires solving a problem that is fundamentally hard even for computers.

The Super Rotation System (SRS), introduced in the 2001 Tetris Guideline by The Tetris Company, standardized how pieces rotate and interact with walls and other blocks across all official Tetris implementations. SRS defines specific rotation states for each piece and a system of wall kicks, offsets applied when a standard rotation would cause the piece to overlap with existing blocks or boundaries. The wall kick system tests a sequence of alternative positions, allowing pieces to rotate in tight spaces and enabling advanced techniques like T-spins. A T-spin occurs when the T-piece is rotated into a position that would be impossible without wall kicks, and T-spin line clears award bonus points, adding a deep strategic layer to competitive play.

The seven Tetrimino pieces (I, O, T, S, Z, J, L) are the complete set of free tetrominoes, all possible shapes made by connecting four squares edge-to-edge. Modern Tetris uses a bag randomizer: all seven pieces are shuffled randomly, and the player receives them in that order before a new bag is shuffled. This guarantees that the player receives each piece type at least once per 7 pieces, preventing the long droughts of specific pieces that plagued earlier random piece generators and enabling more consistent strategic play.

Competitive Tetris has evolved into a serious esport. The Classic Tetris World Championship, held annually since 2010, features players competing on the original NES version at speeds where pieces fall faster than human reaction time, requiring players to use techniques like hypertapping (pressing the D-pad at 10+ times per second) and rolling (a grip technique enabling 20+ inputs per second) to keep up with the game's relentless pace.