I think the 'Give Up' button should award gammon or backgammon points based on current position at that time. During multi-game matches, a losing player can 'Give Up' in order to avoid losing the extra points of a gammon or backgammon. The same should go for when a player leaves the room during a game, they should lose by the number of points awarded by the board's current position. Or, you could implement a feature where the player who is giving up can offer a certain number of points, which must be accepted by the other player