en passant chess

• standard chess board and setup.
• a queen, bishop, rook or pawn can be captured by en passant if it moves multiple squares and if one of the opponent's pieces threaten any of the intermediate squares of its movement. when, say, a bishop moves from f1 to b5, if opponent has a pawn at d5, that pawn can capture the bishop by moving to c4 in the next move.
• otherwise standard chess rules apply.