Keys "s"=save "l"=load "b"=back once
The Peruvian Army played this variant in the 1930's. The second board depicts aircraft.
In the sky, the warrior (non-royal king) and queen can only block. The knights are the only units which can capture other planes. Rooks and bishops drop bombs on enemy units below. An unmoved pawn is an anti-aircraft gun and enemy aircraft cannot fly over it.
These are simple illustrations rather than strong opponents.
Bug reports? -- Thank you! Keep them coming!