Pajitnov created TETRIS in 1984, while employed by the Computing Center, part of the Academy of Sciences of the USSR, a government research and development agency. The game on display here is a simulation of his original program—a two-dimensional geometric spatial puzzle. Various four-part shapes, called Tetriminos, fall in random order down the vertical playing field, known as the Matrix. The player must move and rotate each Tetrimino as it falls in order to complete a horizontal line of ten blocks across the bottom of the screen. When this is accomplished, the line vanishes. Once several lines are deleted, the player moves up a level; as the player succeeds, the Tetriminos fall faster and faster. The game is over when the stack reaches the top of the Matrix. In the mid-1980s, TETRIS was licensed for a range of home computer systems, in addition to arcade cabinets; Nintendo included it in 1989 on the handheld portable Game Boy player, rocketing the game—and the device—to fame. With its universal appeal, TETRIS has been adapted to nearly every video game or computer system and to devices including consoles, mobile phones, personal computers, and tabletop games.