Tetris 99 is a puzzle video game and an online multiplayer adaptation of Tetris. Players move and drop puzzle pieces called tetrominoes onto a playing board, and must clear rows by filling them completely with pieces. Players lose if tetrominoes overflow off the top of the board or their next piece is not able to spawn because it overlaps an existing block on the playfield. Matches contain 99 players, who send additional rows to other players' boards by clearing a row on their own board; whoever is the last man standing without an overflowed board wins the match.