"The Unique Challenge With a Touch of Class" From the back of the box: "OD BALL is played very similar to the ancient Chinese game called NIM. Each player alternates turns in which any number of balls may be eliminated from any one of the three sections. Players may eliminate only one ball or the whole section or any number in between - but only from one section at a time. The winner is the player who forces his opponent to take the last ball." Instead of the piles of sticks or stones usually used for NIM, it has marbles which are captured in a wooden board. Each marble can be snapped down to a lower position to take it. The board is double-sided, allowing play to continue after all the marbles have been taken.