The concept is cool and the graphics are really good and cute but I think the execution was not as good as the idea. There is not much to do besides jumping and collecting the gems. Maybe adding enemies and different scenarios would make it better but still it would be just like any platformer out there. Try to implement a mechanic were you need to use your gems to rewind or to pass trough certain doors idk, use your creativity.
Anyway, it was a good game with good story but it is not very fun. Hey, try my game and rate/review it as well, I bet you would like!