Rock blunts scissors... scissors cuts paper... paper covers rock!
The game board is covered in a mix of rocks, paper and scissors. Your job is to capture each one until only one item is left. A rock can be moved to capture a scissors that's beside it, but it can't capture paper or another rock. And similarly for the other types.
There is always a solution. You can select from four different difficulty levels, which just affect the size of the board.