MULTI PLAYER CHESS
An identical chess set is required for each player involved, for tournament games each chess set should be numbered and each chess piece should be labeled underneath with its originating set.
For the purposes of this description, 4 players (A,B,C,D) and 4 chess sets (1,2,3,4) will be used - however any number of players/sets 3 or more can be used.
Set up each of the four players playing white versus 1 player and black versus another player as in the diagram (the rectangles represent playing colours).
If clocks are used set up the four clocks with TWICE the normal playing time (e.g. if your players normally play 30minute clocks - set the clocks to 1 hour.).
Each player plays according to the normal rules of chess (with exceptions noted below) versus two players simultaneously (one game as white the other as black).
Each player keeps all pieces captured in a stockpile for further use (see below).
The moment any player calls checkmate against a player, all games are temporarily halted, the player who has just lost is eliminated from the circle including his stockpiles and the board the losing game was played on. The circle is then closed in - the game still in play by the eliminated player is taken over by the winner of the just lost game ( in the diagram if B lost his game against A, B is eliminated along with his stockpile - then A commences playing of the game which was being played B vs C. A brings his stockpile into that game).
If multiple players calls checkmate simultaneously, then the above process is repeated for each player.
The winner is player remaining after all other players have lost one game.
If all remaining players call checkmate simultaneously the result is a draw between all players.
Each player keeps white and black pieces taken from both games in a stockpile. The stockpile is used to restock your board with pieces. For example if B captures a knight from C in that game, B can use that knight to re-enforce his position in the game B is playing against A.
Pieces can only be placed on the board in their starting position.
The King cannot be stockpiled.
A piece cannot be placed on a board to counter a checkmate, however it can be used to counter a check.
A piece from a given board cannot be replaced on that board, that is a rook from board 1 that moves around the board to be in the stockpile of a player on board 1 is removed from the game (for simplicity of setup this rule can be ignored in social games).
A piece cannot be placed in such a way as to introduce an illegal situation, although they can be placed in such a way to achieve what appears to be an 'unachievable' situation.
A piece newly placed onto a board is considered to have NOT moved for the purpose of castling and initial pawn move and any other rule that assumes a piece has not moved.
4. Rule Variations
A stalemate can only occur when stalemate conditions are met for both of a players games. In that case that player is considered to have lost ONE of the games (the losing players choice). At the moment stalemate conditions are met for both a players games, proceed as if checkmate had been called on the game of the players choice.
'Queening' a pawn can only be done using your stockpile, the pawn is removed from the game (does not enter a stockpile) and the player can place the new piece at any legal position on the board (not just in its starting position). This piece is considered to have moved for the purposed of castling etc.
Queening a pawn into another pawn is not allowed.
Strategies are a little different depending on if there is an odd or even number of players. With an odd number of players it can be of benefit to sacrifice to one player to improve your place in the other. With even number of players it is generally best to play to win on both boards.
The important thing to remember is you only have to lose on ONE of the two boards to lose the whole game, so be careful with your stockpile, and think about how one of your opponents can help you on the other board.