Kriegspiel is a
Chess Variant. It is played between
two players. However, a third person is necessary to act as a
referee.
In Kriegspiel, players only see their own pieces, and not the pieces of their opponent. Three boards are necessary for the game: one for each player, on which only the player's pieces are placed, and one for the referee, on which all the pieces are placed (the pieces for both sides).
Players move turn-wise, just as in regular chess. Each turn, a player attempts a move. When this move is legal, the referee announces that the player has moved, and the turn is done. When the move is illegal, the referee announces that the player attempted an illegal move, and the player must make a new attempt to move, until he makes a legal move. The other player does not hear the attempted moves, but all referee comments
are heard by both players.
When a piece captures another piece, the referee announces this, and also the square on which the capture has taken place. The referee does not announce with which type of piece the capture has been taken place, or which type of piece is taken. If a piece is captured en passant, the referee announces this. So, for example, the referee could announce "White has taken en passant on b6."
When a move gives check, the referee announces this, and also announces the direction in which check is given: on the row, on the column, on the small diagonal, on the large diagonal, or by a knight. The exact location of the checking piece is not told.
To avoid many attempts at pawn captures, which would usually happen, a player is allowed to ask "Are there any pawn captures?" (usually just "Any?"), to which the referee replies either "No", or "Try." If there are possible captures, the player must attempt at least one. (If it fails, he does not have to try again.)
If player makes a move which he knows is illegal (for instance, asking "Any?" when he has no pawns left), the referee says "Impossible", so the opponent is not confused by this. This is usually considered bad manners, and is not done.
This game may sound as if it's based on luck, but it is really not. Of course, there is more luck involved than in regular chess, but a great amount of skill is necessary to play it.