Reversi is a two player (in single-player games between the player and a CPU) game where players alternately place stones, one at a time, on a grid. The stones have opposing black and white faces, with one of the colors being allotted to each player. A valid move must be in a straight line between the new stone and another stone of the same color already on the board, thereby capturing at least one of the opponent’s stones in between. Captured stones are flipped to show the other color. If a player cannot find a place to put their stone in making a valid move, as they take alternate turns, the other player gets to make additional moves until they can. The game ends when either the entire grid is filled in or both players can no longer make valid moves. The player with the most stones on the board wins.