You play Black; Black moves first. A move must flank at least one opponent disc — all flanked discs flip. If you have no legal move, your turn passes automatically.
You play Black, the AI plays White. Each move must place a disc so it sandwiches one or more of your opponent's discs in a straight line — horizontal, vertical, or diagonal. Every sandwiched disc flips to your color.
If you have no legal move, your turn passes automatically. When neither side can move (or the board fills up), the side with more discs wins.