My thoughts:

Good -
cool requires a lot of thought and precision
Cool level design
Like how the background changes colours
Some level variation

Bad -
Lighting not very good
Menu UI not very nice

Its a paid game but there is not enough content there to make people feel willing to pay for it. Also the graphics and lighting wont help sway people over either. You say you want to raise 500 for the game however no offense but that is just unrealistic for a game like this. 

I think if you added more content and polish as well as improving the graphics a lot more people could be willing to purchase it.

A good idea would be to try a proper game engine like unity or godot to make the game properly. These are just my thoughts your game was still good i enjoyed playing it!