Would you enjoy more of this game concept?
Personally no, but that's fine! I just don't like puzzle games or chess. I think there are plenty of people who would really like this. It got too hard for me once you had both characters and boxes to push.
I think the easiest way to improve it would be to add some sound effects! A nice sliding sound on the rook and a satisfying 'thock' when the knight moves would make the game feel more alive. Some sort of sound to reward the player for collecting treasure would be nice too.
I agree that the music should loop, maybe you could add a mute button if you're concerned about it getting annoying.
The gameplay is great as-is, nice job! I haven't seen a game like this before.