Play against the computer or a friend. Reversi is a lot like checkers — to win you need to have more pieces on the board than your opponent by the end of the game.
The game pieces are black or white. If you play against the computer you start as the black pieces. Each turn, you put a new piece on the board — you'll get a hint at where you can put it. When you put a piece next to an opponents', you capture it and it flips over to your colour. Play until the board is full and no more pieces can be capture. The player with the most pieces wins!