Kriegspiel

Kriegspiel is a chess variant based on lack of information. You will need three people, three chess boards and two chess sets in order to play. The two competitors each sit facing opposite walls with a chess set set up in front of them. However one player can only see the white pieces and the other can only see the black pieces. In between them a third complete set is used to track the game by the host.

Play starts with White trying to move a piece (silently) to which the host will respond by saying yes and before moving it on the central board that neither player can see. Then it is Black's turn and they will also play a move, even though they have no information about what the first player has done. As play progresses players will start making moves which are not possible (i.e. there was a piece in the way) in which case the host will simply say no and they can try again. If you take something the host will announce Pawn Taken, or Piece Taken (pawns aren't pieces) and that piece will simply disappear from one of the boards.

Since you don't lose anything from trying all of the possible pawn attacks every turn, it is a convention that if there is a possible attack from one of your pawns then the host will just tells you. This makes pawns useful scouts as you try to find the layout of your opponent's fortress. Other things which are announced for everyone to hear are checks (and which direction they come from) as well as draws, checkmates etc. Promotions, castling and en passant are not announced.

I played a game today which I accidentally stalemated with 2 Queens and 2 pawns against a king. I also hosted a game which ended in a checkmate in the middle game. Both players managed to win a queen with different tactics, but I wanted to point out a clever gambit: if you assume that in most games the King's pawn is going to come forwards, then as Black you can move your Queen's Pawn forwards and then move your light squared bishop to g4. It is a terrible move in normal chess because the Queen can just take it, but if they don't know it is there then you can take their unsuspecting Queen from its starting square on your 3rd turn.