Super fun idea and if I'm being honest, very similar to one we discarded because we were afraid it wouldn't be so fun.
Happy to say we were wrong and it's quite enjoyable :)
If I can suggest a fix, it would be nice to clamp the mouse position to the window (so it doesn't loose focus). I've been wondering a few times why I couldn't move anymore and I think it's because I clicked out of the game window.
Very nice entry all in all, I'd be interested to see more of it!