Chess Contradance
Karen Robinson invented this chess-based puzzle, based on a puzzle from the computer game `The 7th Guest' (a puzzle game with a horror theme), which her son played.Hans Bodlaender first named this game `Chess Squaredance', but it was renamed later `Chess Contradance', as Karen Robinson remarked that the setup is more like a contradance with the two lines facing each other.
Rules
Set the pieces up as in regular chess, but without the pawns. The first and eight ranks are safe havens, i.e., no piece can be captured on these ranks. The object of the puzzle is to move the pieces such that all pieces of one color trade places with the pieces of those of the other color, but no piece may ever move to a square where it could be captured. Make alternately white and black moves.In the easier variant, one should just move all the pieces to the other side of the board without paying attention to the final ordering of these pieces. In a harder variant, the setup at the end should be the same as at the beginning with only colors reversed, e.g., there should be a white rook at a8, etc.
Comment
This puzzle may be quite hard. Email me how many moves you need in your solution, and I'll publish the best attempts of both variations.Written by Hans Bodlaender, based on email of Karen Robinson, who stated `I don't know whether my variation is really original or not'.
WWW page created: November 6, 1998. Last modified: November 11, 1998.