Tell your opponent to choose the hand containing the pawn - if they guess correctly, they go first. Otherwise, you do. Any piece positioned on your side of the Centerline belongs to you - only you may move it. The upshot of this is that anytime you move a piece across the Centerline, it suddenly becomes your opponent's piece. You may only capture pieces belonging to your opponent, i.e. pieces on the other side of the Centerline.
All pieces move as they normally do except for Pawns, which can move in either direction.
Nothing special happens to Pawns that advance to the 8th square. Pawns may move 2 spaces towards the center line anytime they are in one of the Pawns' normal starting squares. As in Normal Chess, pawns may only move forward if the path is unobstructed, and they may only capture diagonally. No limitations are imposed on Castling, except that no pieces may obstruct the path between King and Rook. In other words, the rule that neither piece have been moved prior to a Castle and the rule that prohibits Castling across Check are discarded.