Click on two matching tiles to clear them from the board. There are four of each type of tile. The red tiles match all other red tiles (regardless of the picture) as do the green tiles. Also, all the quarter moons match regardless of direction. A tile is free if either the right or left side is not blocked by another tile. It is possible to reach the position where all free tiles have been removed from the board (but some tiles remain) and lose. If you remove all the tiles—you win!