Rule ZeroMost chess variants begin with a basic set of rules which are explained over and over in one game description after another.
This is an attempt to codify those rules so that a simple reference to this document can be used in new games to save the writing of several repetitive paragraphs.
Rule Zero of Rule ZeroThe rules of FIDE Chess apply except as follows.
CastlingThe King can Castle with whatever piece is in the corner, even though that piece is not a Rook, and of course the usual restrictions and rules on Castling apply.
If the piece on the a-file is colorbound, castling Queenside involves moving the K to the b-file and the other piece from the a-file to the c-file. This is not optional, and the reason for the rule is that the colorbound piece must land on a new square of the same color.
In games where moving pieces has side effects, Castling counts as moving two pieces.
PawnsA Pawn that reaches its eighth rank is promoted to any type of piece (other than King or Pawn) that is in either player's army; its owner makes the choice.
A Pawn on the second rank can make its two-step move even if it has previously moved or been moved. When it does so, it is subject to en passant capture.
KnightsIn some games, Knights cannot leap over obstacles.
Unless the rules of the game specify otherwise, a non-leaping Knight is considered to move first Rookwise and then diagonally; and so, a non-leaping Knight on b1 can go to c3 even if c2 is occupied but if b2 is occupied it cannot go from b1 to c3.
Object of the GameIn FIDE Chess, it does not matter whether the object of the game is to capture the King or to checkmate the King. In many chess variants, however, it does make a difference.
Unless a variant specifies that the game is won by capturing the King, or of course unless it specifies some other object entirely, the object is assumed to be checkmate.
Another common case is when either stalemate or checkmate wins the game.
When Checkmate is the ObjectIf a move has multiple parts, you may not leave your King in check (nor may you put your K in check) in an earlier part and cover the check in a later part of the move.
When King Capture is the ObjectAll rules about check can be ignored except those relating to Castling.
When Stalemate WinsWhen stalemate wins, it is forbidden to repeat an earlier position on the board.
General RulesIt is forbidden to make a null move, that is, a move that has no effect. For example, a Go Away in Nemoroth cannot scream if there are no pieces to push, and a Rook in Cylindrical Chess cannot move sideways around the edge of the board and land on its original square.
In games where there are neutral pieces, it is forbidden to make a move with a neutral piece that simply undoes the move just made by the opponent with the same piece.
Written by Ralph Betza.
WWW page created: June 28th, 2002, Updated June 26th, 2002.