Keys "s"=save "l"=load "b"=back once
This is a simple chess variant which was manufactured early in the 1900's. Pawns move one square orthogonally, and can jump a piece of their own color though not to capture. Otherwise pieces move as in normal chess. Win by capturing the opposing king ("the citadel"). I let the program call "Check" and "Mate". Stalemate is a loss for the side unable to move.
These are simple illustrations rather than strong opponents.
Bug reports? -- Thank you! Keep them coming!