Chess: Secret King

Chess: Secret King is a chess variant where each player secretly chooses any of their pieces to be their king. If you manage to guess which piece is your opponents king, and take it too, you win! This present version is local PvP only, though online PvP is in development.  Still a work in progress, both checks and pawn promotions are disabled- let me know if you think either of these mechanics would improve the game and why!