if you ever make a sequel, here are some ideas!
King: Playable piece that cant die at all costs
Bishop: Diagonal rook, basically, like in chess.
Queen: Basically a rook and bishop. like in chess
Promotion squares: Squares that can let a pawn promote.
Knight: Piece another piece can mount, which has the classic L shape movement, and jumps over anything, but can only move ONCE. (it can only move when a piece gets on it)