A really cool concept. I've never seen this kind of chess interpretation before, but there's one issue. I think the king should keep his standard movement pattern – in one of my games, the king moved like a queen, and I just couldn't deliver checkmate. Maybe revert to the standard movement if only the king remains? It's awesome that you added not just PvP but also a bot mode. Did you use a chess engine for this, or did you code everything by own?