Tetris
In a game of Tetris, shapes known as tetrominoes fall down into a playing field, which is usually ten squares wide and twenty squares tall. There are seven different tetrominoes.  The goal of the player is to move and turn the falling tetrominoes so they fill an entire row of the playing field. When a row is completely filled, it disappears and the lines above it move down to fill the space. This is called a line clear.