Players have to maneuver and stack block pieces to form horizontal lines to eliminate rows in this revolutionary puzzle game. A rectangular play field is 10 squares wide by 20 squares high. One at a time, at the top of the field, the player will be given one of seven tetromino pieces (consisting of four square blocks each), shaped like a square, “z,” backwards “z,” “L,” backwards “L,” “t,” and an ”I” piece.