Additional rules for multiplayer chess variants
by Derick R. Peterson, 10/08/97
Derick R. Peterson created the following additional rules for multiplayer
chess variants, In an effort to lessen the inherent lack of fairness and
petty diplomacy problems of such a multi-player perfect information strategy
games. The rules are stated in general for any n-player chess variant where
more than 2 players or teams are competing to be the sole victor.
(1) Defending from multiple attackers
When one player is simultaneously threatened by k (1 < k < n)
opponents, he is entitled to move up to k of his pieces during his turn
subject to the following restrictions.
- No piece may be moved more than once.
- He may not capture more than one piece belonging to any one opponent.
- He may not threaten or capture any more than one new piece belonging
to any one opponent unless all but one of his attacks on that opponent
simultaneously attack pieces of other opponents.
- Unless he can simultaneously check or checkmate all of his k attackers,
he may not use more than one of his moves to enforce checkmate on any one
player even if the checkmating piece simultaneously attacks another opponent's
- None of his moves can expose his king to check even if his next move
in the same turn could parry the check.
(2) Fair exchange of pieces per round
When any k players exchange pieces in the course of one "round"
of moves, those n-k players not involved in the exchange are obliged to
remove pieces of equal or greater value than the weakest piece involved
in the exchange subject to the following restrictions.
- No player is obliged to remove his king or any piece which exposes
his king to check.
- Here a "round" is defined to be a series of n players' turns,
beginning with one player's capture of an opponent's piece.
- The players forced to remove their own pieces may choose which piece
or pieces to remove, and these pieces are not removed until their turn
following the round of exchange.
- Any player forced to remove pieces may choose to exchange a powerful
piece for any of his captured pieces whose powers are a proper subset of
the piece which is being exchanged. For example, a live queen can be exchanged
for a captured rook or bishop but not a knight or pawn. The weaker exchanged
piece must, of course, be placed on the square vacated by the more powerful
hostage; note that this determines the color of a bishop taking the place
of the queen, for example.
(3) Checkmate and capture of a king
- A player is not out of the game until his King is actually captured.
- When his King is captured, his pieces remain on the board as immovable
obstacles for the remaining players to navigate. If all players agree in
advance, these pieces may be captured to remove them from the board; otherwise,
these obstacles cannot be captured nor removed.
- When a player's King remains on the board, but he is in checkmate,
he loses his turn until the checking piece withdraws. However, while in
a checkmate freeze, except for his King that player's pieces are immune
to attack from all other players.
Written by Derick R. Peterson. Edited by Hans Bodlaender.
WWW page created: February 10, 1998.