Keys "s"=save "l"=load "b"=back once
In this co-chess variant, hostile units on co-squares are turned into zombies that cannot capture, act as part of a co-pair, check, (if a king) castle, (if a pawn) make an initial double move or promote.
They are restored to normal by finding themselves on a friendly co-square. To save programming space, I made these pawns promote to queens.
Pritchard offers the name "Zombie Chess" for this variant.
These are simple illustrations rather than strong opponents.
Bug reports? -- Thank you! Keep them coming!