Shapes called blocks fall, one at a time, from the top of the playing field to the bottom. 4 squares arranged into 7 different patterns. The object of the game is to keep the blocks from piling up to the top of the playing field. To do this, the player must move and rotate the blocks as they fall, attempting to fit them together. If the player can completely fill one horizontal line with colored squares, that line disappears and any filled squares above move down. If the player is unable to fill lines completely, the tetrads will stack up and eventually reach the top of the playing field. The game ends when a new blocks that is placed at the top of the playing field is unable to drop at all due to the filled blocks.