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 Blocks 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. The different blocks of tetris: I-blocks are useful for competing four lines at once. O-blocks for filling large gaps. L-blocks for filling medium-sized holes. J-blocks face the opposite direction as L-blocks. S-blocks for filling small holes. Z-blocks face the opposite direction as S-blocks