The game starts with the standard four center stones on an 8 by 8 board. A legal move must trap one or more opponent stones in a straight line across any of the eight directions, then those trapped stones flip to your color.
When a player has no legal move, the turn passes automatically; the game ends when neither side can move, and the side with more stones wins. The CPU uses a shallow local minimax search with piece-count scoring, so it is intended for casual play rather than official Othello rating or online match history.