Keys "s"=save "l"=load "b"=back once
Four-Handed Chess III was supposedly a hit at Gen Con a few years back. Win by capturing the last king. Units belonging to a player in checkmate cannot be taken and but do give check until the king is captured. I think that the latter can cause some contradictions but these are rare. If you are in checkmate or otherwise cannot move, then your turn passes. Capturing the king makes the starting squares vanish. I have all promotions as queens.
These are simple illustrations rather than strong opponents.
Bug reports? -- Thank you! Keep them coming!