Maybe you should put the rock in the middle since it is the main object?
Make the parallax faster since the rock needs to move fast; increasing parallax speed will help with that effect. Add some progression, like going very fast, then slowing down as the rock loses its velocity.
Also, it would be good if, when I enter the shop when the game is over, and when I press X, it just closes the shop UI; don't move me back to maenu, that will be a good fix; make better mapping of buttons
When fully upgraded, skip, the sound is so bad, and it doesn't stop; very bad