Playing Kriegspiel on ICC internet server. Umpire announcement (made by a computer) are shown at the bottom.

Kriegspiel is a chess variant in which each player can see their own pieces, but not those of their opponent. For this reason, it is necessary to have a third person (or computer) act as a referee, with full information about the progress of the game. When it is a player's turn he will attempt a move, which the referee will declare to be 'legal' or 'illegal'. If the move is illegal, the player tries again; if it's legal, that move stands. Each player is given information about checks and captures. They may also ask the referee if there are any legal captures with a pawn. Since the position of the opponent's pieces is unknown, kriegspiel is not a game with perfect information. Chess kriegspiel was used in 19th century Germany to train military officers. Image File history File links Download high resolution version (638x867, 181 KB) Summary Playing Kriegspiel (chess) on Internet Chess Club, using BlitzIn 2. ... Image File history File links Download high resolution version (638x867, 181 KB) Summary Playing Kriegspiel (chess) on Internet Chess Club, using BlitzIn 2. ... The Internet Chess Club is a commercial Internet site devoted to the play and discussion of chess and chess variants. ... A chess variant is a game derived from, related to or similar to chess in at least one respect. ... In games such as chess, shogi, and xiangqi, a check is an immediate threat to capture the king (or general in xiangqi). ... Perfect information is a term used in economics and game theory to describe a state of complete knowledge about the actions of other players that is instantaneously updated as new information arises. ... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... In military organizations, a commissioned officer is a member of the service who derives authority directly from a sovereign power, and as such holds a commission from that power. ...

Rules

There are several different rulesets for Chess Kriegspiel. The most widespread rules are those used on the Internet Chess Club, where Kriegspiel is called Wild 16. The rules are as follows.

The game is played with 3 boards, one for each player and one for the umpire (and spectators). Each opponent knows the exact position only of her own pieces and doesn't know where the opponent's pieces are (but can keep track of how many there are). Only the umpire knows the exact current position of the game. The game proceeds in the following way. The umpire announces:

• White (or black) to move.
• Pawn tries, when it is possible for one's pawn to capture an opponent's pawn or piece. The umpire also indicates the square on which the capture is possible to the player who can make the capture. This gives extra information, but saves both players the bother of beginning every turn by trying all possible pawn captures. This is possible at no risk because pawns don't move the same way they capture. Hence, if no capture is possible, then the move is illegal and there is no penalty for attempting illegal moves. A pawn try is not announced if the pawn is pinned, i.e., completing the capture would expose the king to check. En-passant pawn tries are announced, of course, but not the fact that they are en-passant captures.

• Pawn gone, when a pawn is captured.
• Piece gone, when a piece is captured.
• No, when the move which the player attempted is illegal, given the opponent's position. For example: moving the king into check; moving a queen, rook, bishop, or pawn through squares occupied by the opponent's pieces; advancing a pawn into a square occupied by the opponent's pieces.
• Hell no (or Impossible), when the move which the player attempted is always illegal regardless of the opponent's position. For example, moving a bishop a knight's move.
• Check on the vertical.
• Check on the horizontal.
• Check on the long diagonal (the longer of the two diagonals, from the king's point of view).
• Check on the short diagonal.
• Check by a knight.
• Checkmate, stalemate, draw by repetition, draw by insufficient force, 50-move draw.

Pawn promotions are not announced.

Kriegspiel problems

Jacques Rotenberg
The Problemist 1976

Kriegspiel, mate in 8. Black has a bishop somewhere on dark squares, not exactly known where.

Kriegspiel is sometimes used in chess problems. In these, usual variations introduced by different black moves are replaced by variations introduced by different announcements. Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... 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Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Image File history File links This image is used in the standard chess diagram template. ... Sam Loyd, London Era, 1861 Excelsior by Sam Loyd. ...

An example of a Kriegspiel problem is shown at the right. White must checkmate Black in 8 moves, no matter where the black bishop initially is (it is somewhere on dark squares) and no matter what black plays. (Note that in a real game, black would not see white's moves, but for a problem in which white is to force a win, one must assume the worst-case scenario in which black guesses correctly on each move.) For example, 1. Ra1?? is a draw by stalemate if the black bishop was initially on a1. 1. Nf2 Bxf2 2. Kxf2 (or Rxf2) is stalemate as well. So, white should not move either the knight or the bishop, because either might capture the black bishop by accident. For the same reason, the white rook should move only to light squares -- but only half of the light squares are reachable without visiting a dark square along the way.

The solution is the following. White tries to play 1. Rg2.

• If this move is not possible (umpire says No), then the black bishop must be on b2, d2 or f2. In this case white can instead play 1.Nf2# (checkmate).
• If the move is possible, it is made and then black moves the bishop. White still doesn't 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 possible, white continues 3. Rh8. (This is safe -- the black bishop can't be on h8 to be captured, because it wasn't on g7 on the previous turn.) 4. Rh5 5. Rb5 (if not possible, 5. Rh3 and 6.Be5). 6. Rb1 7. Nf2+ Bxf2 8. Kxf2#.

References

• D.B. Pritchard (2000). Popular Chess Variants. ISBN 0713485787.

External links

• Kriegspiel by Hans L. Bodlaender.
• SchemingMind.com, internet server to play Kriegspiel.
• Berkeley Kriegspiel Home, Kriegspiel in Artificial intelligence research.
• Bologna Kriegspiel Home A page on Kriegspiel research
• U. Maryland Kriegspiel Home A page on Kriegspiel research