must be on b2, d2 or f2. In this case White can instead play 1.N(x)f2. If the move is possible, it is made and then Black moves the bishop. White still does not know where the bishop is. White continues with 2.Rg8. If not possible, then black bishop is on g3, g5 or g7. White plays 2.Be5. If Black now plays 2...Bxe5, 3.Nf2#. Otherwise (any move by Black) 3.Nf2+ Bxf2 4.Rxh2#. If 2.Rg8 was possible, White continues 3.Rh8. (This is safe – the black bishop cannot be on h8 to be captured, because it was not on g7 on the previous turn.) 4.Rh5 and 5.Rb5. If 5.Rb5 was possible, White continues 6.Rb1 7.Nf2+ Bxf2 8.Kxf2#. If 5.Rb5 was not possible, then 5.Rh3 (the black bishop must be on c5, e5 or g5 at this moment) 6.Be5 (this is safe because before 6.Be5 the black bishop had to make a move from either c5, e5 or g5, thus cannot be on e5 at this moment) 7.Nf2+ Bxf2 8.Rxh2#. If 4.Rh5 or 6.Rb1 (after 5.Rb5) are blocked (umpire says No to these moves), then the black bishop is not guarding f2 at that particular moment so White can immediately play Nf2# instead. Rule variations Edward Nathan Frankenstein suggested in 1903 a variation of the game where one player sees the board and another plays Kriegspiel. To make the game fair, the "sighted" player starts with fewer pieces. Frankenstein proposed two variants: Pickle pot: The player who sees the board plays with king, queen, one bishop, and pawns; a total of 11 pieces. One-eye: The player who sees the board plays with king, two rooks, one bishop, and pawns; a total of 12 pieces. In both versions, it should be announced which bishop is used (on c-file or f-file). Semi-kriegspiel: The game is similar to these variations. The "sighted" side has only king and queen, which can be placed on any legal square before the beginning of the game. Suggested by David Silverman (1971). Modern kriegspiel: After each move, the player calls seven squares, which must be opened by umpire. Otherwise the rules are as in usual kriegspiel. By Bruce Trone (1986). Combining Crazyhouse with Kriegspiel yields Crazyhouse Kriegspiel (or CrazyKrieg for short). In shogi, the game analogous to kriegspiel is called tsuitate shogi (). See also Dark chess Fog of war References External links Kriegspiel by Hans L. Bodlaender, The Chess Variant