Reversi: Pass and Play
Two players, one screen. Outflank your opponent's discs to flip them.
How to play
The board: eight by eight squares, starting with two black discs and two white ones in the middle. Black moves first, then the players take turns.
A move: put a disc of your color on an empty square so that it outflanks some of your opponent's discs: a straight line of them, across, down or diagonally, with your new disc at one end and another of yours at the other. Every disc you outflank, in every direction at once, flips over to your color.
Passing: if you have no move that outflanks anything, you pass, and your opponent moves again. You can't pass if you have a move.
The end: the game ends when neither player can move, usually when the board is full. Whoever has more discs wins. Any squares left empty count for the winner.
Tips: corners are worth a lot, because a disc there can never be flipped; the squares next to an empty corner can give it away. The dots show where the player to move can play; point at one to see which discs it would flip, and the red dot marks the last move. Undo takes back the last move, whoever made it. Click a name to change it. The bar above the board is who the computer thinks is winning; near the end of the game it works out perfect play for both sides, and shows that result instead.