✦Castling — Move your King 2 squares toward a Rook; the Rook jumps to the other side. Only valid if neither piece has moved and no squares between them are occupied or under attack.
✦En Passant — If a pawn advances 2 squares past an enemy pawn, that enemy pawn may capture it as if it had only moved 1. Must be done immediately on the next move.
✦Promotion — When a pawn reaches the far end of the board it transforms into any piece (Queen, Rook, Bishop, or Knight). A panel will appear — tap your choice.