Snap Go

SnapGo is a variant of Go that includes, both directly and indirectly, rules from the card game Snap.

1. Whenever a player takes a stone from their bowl and places it on the board, should they or their opponent notice that it is the same as an existing stone on the board, then they may shout Snap! and remove the two matching stones.
2. Should an incorrect claim of Snap! be made by a player, then they can be given a 3 point penalty, provided their opponent objects before the next play is made.
3. Normally, only stones which are present on the board are subject to the Snap! rule. Prisoners are generally deemed to be exempt.
4. Stones that are snapped are themselves treated as prisoners.

Example, Black plays  

White prevents Bent 4 by Snap!