Keys "s"=save "l"=load "b"=back once
R. Wayne Schmittberger, 1983. The king may move to, and only to, any square supported by a friendly unit and not attacked by an enemy unit. The king must always have a defender.
I did allow the king to move to a square which would only be supported by a friendly unit after the move, i.e., it is not enough simply to move orthogonally from a friendly rook or diagonally away from a friendly bishop.
These are simple illustrations rather than strong opponents.
Bug reports? -- Thank you! Keep them coming!