The game consists of a 10x20 grid where tetrominoes (shapes composed of four square blocks) fall from the top. The objective of the game is to manipulate these tetrominoes by moving them sideways or rotating them, with the aim of creating a horizontal line of ten blocks without gaps. When such a line is created, it disappears and any blocks above it fall down. The game ends when the grid is filled up and no more tetrominoes can fall.