- Group: a set of connected, like-colored stones on the board.
- To drop: to place a stone on any empty cell.
The game starts on an empty board. There are two players, white and black.
Note that there's no actual counting involved in the non-parity rule: just keep it odd.
The position on the left side of the board shows 5 groups total. If a black stone is dropped at 'A', there will be 2 groups less on the board, so parity doesn't change. On the right side a legal move for any player has been made. Note that the second placement doesn't change parity, either.
|The position on the left side of the board shows 3 groups. Dropping a black stone at 'A' reduces the group count by 1, so the total number of groups will be even. The second move of the turn must change the number of groups back to an odd number, as is shown on the right.|
|On his turn, black would like to join his two groups by playing black stones at 'A' and 'B', but he can't. That would reduce the total number of groups to 4, and he would need another move to restore the group count to an odd number.|
|Here both players have passed. Black has 2 groups to white's 3, so Black wins. Note that White can't join his groups at 'a' because there is no way to restore the group count to an odd number afterwards.|
|The diamond connection is still unbreakable, unless the opponent can fill the intermediate cells by growing one existing group at one of the marked cells.|
Using the Xodd applet
Yodd © Luis Bolaños Mures
Java applet © Ed van Zon