Keys "s"=save "l"=load "b"=back once
This is a very popular variant by V.P.Parton (1953). When a unit moves, it is transferred to the corresponding square on the other board. A move must be legal on the board where it is made. A move may only take a unit to a square if the corresponding square on the other board is vacant.
I originally misunderstood and thought pieces on the mirror board blocked movement. Thanks to Ty Baen for pointing out the error (11/5/03). Erik Maranus pointed out to me (3/19/06) that a piece can interpose to save a king in check by moving from the other board. I had originally misinterpreted this as illegal because the move would not by itself be legal on the other board. However, examining the model game in "Pritchard" satisfied me that he is correct.
Thanks to Arnold Preston (12/7/06) for reminding me that because a move must be legal on the original board and that a king therefore must not move into check. The error has been corrected.
Thanks to Monwhea Jeng for more help debugging (1/1/07).
These are simple illustrations rather than strong opponents.
Bug Reports -- Thank you! Keep them coming!
Written by Ed Friedlander
WWW Page Added: Sunday, December 30, 2001