Good job. Very solid game. The parallax effect is really nice and the graphics are good.
Unfortunately, I'm not sure how you used the theme in your game. Did you not use it or did I not get it?
Correct me if I'm wrong, but it seems your are a fan of Blackthornprod because used a lot of stuff out of his tutorials. ;)
Oh, some stuff to improve your game:
- First to the bug. The highscore keeps increasing when you are dead :D
- I did not see any increase in difficulty in your game. Maybe you could speed up the game after some time.
- Your mouse pointer is behind the UI elements. The problem here is that you used a gameobject for the mouse pointer, but you should use a UI element (image) which follows the mouse position.