Goal
Finish with more discs of your color than your opponent.
Your turn
Place one disc on an empty square so that it flanks a straight line (row, column, or diagonal) of one or more opponent discs, capped at each end by your own discs. Every flanked disc flips to your color. You may only play where at least one disc flips.
If you have no legal move, you pass. When both players pass in a row — or the board fills — the game ends and the player with more discs wins.
Dark moves first.