In 1968, this variant has been invented by Hans Kluever and Peter Kahl. It still is popular in postal chess variant organisations like NOST and AISE. While the rules may look complicated at first sight, they appear at second sight quite natural.
The game is played with a normal set of pieces, from the normal starting setup.
Pieces have the same movement as in orthodox chess, except that they cannot take other pieces in the way of orthodox chess. Additionally, pieces can pull or push other pieces. Taking is done by pulling or pushing other pieces off the board.
Each turn, a player has the following options.
- He may move one of his pieces.
- He may move one of his pieces, and pull or push another piece with that piece.
- He may pull or push a piece with one of his pieces.
A queen, rook, or bishop pulls or pushes along a line of movement. The effect is that the pulled or pushed piece moves a number of squares in the pulled or pushed direction. When the queen, rook, or bishop moves, the push or pull should be in the same direction as the movement. There should not be any piece between the pulling or pushing piece and the pulled or pushed piece. Also, the pull or push should go to an empty square, or over the edge of the board. The pieces may not pass each other. When a piece is pushed or pulled over the edge of the board, it disappears from the game (it is `taken'). To pull a piece over the edge, the pulling piece also has to disappear over the edge (thus, both the pulling piece and the pushing piece are taken off the board.)
The king and the knight can push or pull a piece they attack. To push, the attacked piece moves in the same direction as the attack (for instance, a knight on a1 attacking a piece on b3 can push the piece to c5). With a push, the knight or king may move to the vacated square or stay at the square they are. To pull, the king or knight move away in the direction opposite from the direction they attack; the attacked piece goes to the vacated square. For instance, a king on e3 can pull a piece on e4 to e3 by moving to e2. Kings and knights can take by pushing a piece over the edge, but cannot take by pulling.
A pawn cannot pull. A pawn pushes a piece of the same color one square straight forward; this must be a square the pawn can move to when empty (when on its opening position, the pawn can push one or two squares forward). For instance, a white pawn on e2 can push a white piece on e3 to e4 or e5 (provided the squares pushed to or passed are all empty), and a white piece on e4 to e5 (provided e3 and the squares pushed to or passed are all empty). A pawn pushes a piece of the opponent one square diagonally forward, provided this piece could have been taken under the normal chess rules. For instance, a white pawn on e3 can push a black piece on d4 to c5. There is no en-passant capture. (Alternatively, one can use the rule that only pawns on the first and last column can be en-passant pushed from the board.)
In all cases, players may push and pull their own pieces as well as pieces from their opponent (for pawns, these are different, see above).
For all pieces, except for the king, it is legal to move from the board, (thus committing suicide). This will often be done in combination with a pull, also taking a piece of the opponent.
When a pawn is pushed or pulled to the 8th row, the playing making the move decides to what piece the pawn promotes.
No push or pull is allowed in the same move as castling. The rule on castling as used in NOST gives all details: Castling may not be combined with a push/pull. A player may not castle into, through, or out of check. A king or rook on its original square which has pushed, pulled, been pushed, or been pulled, may castle as long as it has not moved under its own power.
A king is checked, when it is threatened to be pushed or pulled of the board by an enemy piece. As usual, it is forbidden to make a move, resulting in a position where ones own king is checked. The king is checkmated, when a push or pull of the king of the board cannot be avoided. Object of the game is checkmating the opponent in this way. Stalemate is a draw.
NOST also has the rule that it is illegal to push or pull a king over a square where he is checked (where `checked' again means that he could be pushed or pulled of the board by an enemy piece.)There also is a rule used in NOST that avoids the undoing of the previous move (similar to the `ko'-rule in go): A player may not make a move that restores the position before the previous move. For example, after White's Kd2d3/Kd3d4, Black's Kd4d3/Kd3d2 is forbidden. This rule is also in effect when such a move would be the only way to avoid mate.
NotationIf one wants to play this game by mail or email, one needs a notation. Here is the official notation of NOST: Write the normal move first, followed, if necessary, by a slash and the dynamo move. If the piece remains stationary, simply write its symbol and resting square. If a piece goes over the edge, write 'E' for its final square. Examples of possible first moves in various notations are: Qd1d3/d2d6 or B-KN2/PE or 4143/4246. Capturing without moving is notated like: Bf1/g2E or BKB1/PE or 61/7200.
Written by Hans Bodlaender, with many thanks to Philip M. Cohen, for corrections, and additions. Some sentences were taken from emails from Philip Cohen.
WWW page created: March 11, 1996. Last modified: July 17, 1997.