The Game Boy version of Tetris plays identically to versions on other platforms. A pseudorandom sequence of "tetrominoes" – shapes composed of four square blocks each – fall down the playing field, which is 10 blocks wide by 18 blocks high in the Game Boy version. The object of the game is to manipulate the tetrominoes 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 one or more such lines are created, they disappear, and the blocks above (if any) move down by the number of lines cleared. As in most standard versions of Tetris, blocks do not automatically fall into open gaps when lines are cleared.
As the game progresses, the tetrominoes fall faster. The game ends when at least part of a tetromino extends beyond the top of the playfield when setting in place. The player can normally see which block will appear next in a window off to the side of the playing field, but this feature can be toggled during the game.[5] Points are awarded based on the current level and number of lines cleared. The level increases each time the player clears ten lines, as does the speed of falling tetrominoes.[5] The player may adjust the difficulty before beginning a game by selecting a starting level or choosing to pre-fill the play area with a given number of lines of randomly placed blocks. After completing a particular height, the player is treated to a cutscene of a rocket of various types being launched, eventually capping off with Russians dancing and the Buran shuttle being launched.
This version of Tetris includes a two-player mode, in which each player's objective is to remain in play for longer than his or her opponent. Each player plays with a separate Game Boy and Tetris Game Pak, with the two consoles connected via the Game Link Cable. During gameplay, when a player scores a Double, Triple, or Tetris, one or more incomplete rows of blocks are added to the bottom of their opponent's stack, causing it to rise.