In Edge Chess, pieces are permitted to stand on the edge between two squares, or the corner of four. A piece's moves are calculated from the owner's choice of the spaces occupied. After the move, the piece may be shifted to an adjacent edge, provided the bordering squares are completely unoccupied.
 
The power of a Rook occupying a corner is depicted below.
 
When castling, the rook travels an extra half step, and you have the option of moving the King to an adjacent edge.
 
There is no en passant capture in this implementation.
 
Due to the possibility that the second part of a move may remove check, the loss condition is a King capture, not checkmate.
 
 
Edge chess was invented in 1998 by Mitch Martin of El Dorado and David T. Myers of Diamond Springs, California. This implementation was based on the information at www.edgechess.com.