Hi, the idea is great, and the rolling little ball is super cute :)
I also had the problem of the game crashing after the second level. As an additional suggestion (if you plan to work again on this project), it would be nice to add an animation or a better explanation of how to use the flip-world mechanics, it took me a while to figure it out.
All the bests!
P.S.
Leave a feedback also to my entry, and do not worry to be honest, I really appreciate suggestions that help me to improve :D