This is a variant of
but there is an extra piece, a CASTLE, 2 spaces
ahead of the king. It moves 1 space orthogonally, and may not cross the river.
You may drop piecs you captured as in Shogi, but only orthogonally adjacent to
your castle. If you lose your castle, you may not drop. You may drop across the
river. Pieces restricted to one side of the river stay on the side they were
dropped on. Mandarins may only be dropped in either player's palace, or
diagonally adjacent to a palace, in which it must move inside when it moves