Hidden Move Go
Before the game, both players secretly pick 3 points on the board for their hidden moves. A simple way to record the hidden moves is to draw a square and write for example "3-4" or "10-10" in the general area of the moves. During the game, when a hidden move would affect play, the player reveals the hidden move and places it on the board. If the hidden move makes the opponent's move illegal, he can then choose a different move.
- White tries to play on top of a hidden move. Black reveals the hidden move and places it on the board. White gets to pick a new move.
- White uses his own hidden stone to capture enemy stones. He reveals his hidden move, and makes his own move to complete the capture.
Collisions: If both players make hidden moves on the same point, whoever reveals he has a hidden move there first gets to claim it. Alternatively a neutral judge can check the hidden moves before the game starts for collisions.
Nick Sibicky (a popular proponent of hidden move go) and the variant go server go.kahv.io uses the ruling that if two players pick the same point, neither one gets a stone there.