Latrumcolorum Chess

Rules

FIDE rules follows, except:

If there is an opponent's piece on the board with your pieces on both orthogonal sides (regardless what kind of piece any of them are, even pawn and king), then he cannot move that piece, although you are allowed to move it, according to its normal movement, but now it can capture pieces of either color.

The pawns still move in the direction, and double-step, according to what color it actually is rather than who moves it. The mover of a pawn into its owner's promotion zone gets to decide the promotion (although it still promotes into its own color).

If you move opponent's pieces in this way, you can still move them to put him into check, and/or to get yourself out of check.

Opponent's pieces which are surrounded to give you the opportunity to move them can give check to both players.