Keys "s"=save "l"=load "b"=back once
Grand Chess is considered among the best chess variants. It was invented by Christiaan Freeling.
One may promote a pawn on or after reaching one's eighth rank, only to a piece of a kind which one has already lost. One may not move to the tenth rank until one has lost at least one piece. I programmed this so that a pawn on the ninth rank will still give check -- consider this a local rule.
Hans Bodlaender on Grand Chess
Bodlaender's Chess Variants
Hans Bodlaender's Chess Applet
Ed's Chess Variants
These are simple illustrations rather than strong opponents.
Bug reports? -- Thank you! Keep them coming!