Nothing happens if the game board fills up. The game just goes back and forth between both players but there are no legal moves. Spoiler: Screenshot I also encountered an issue of the double 3's rule. I am not sure if it is supposed to work this way. Please refer to the following image: When I tried to place an omok piece on the blue spot, it did not allow me because it said I cannot have double 3's, but there is only one 3 here.