I agree with a lot of things Tim said! I think some simple adjustments can go a very long way.
The game runs smoothly and the graphics and sounds are cool! And there is a lot you can do mechanically to expand on this project!
Another suggestion that I'd make is to have 'W' also correspond to a jump key. I noticed that I could move right or left with (Left arrow and Right arrow (OR) 'A' and 'D') but I could only jump with Up arrow. Just a suggestion.
Cool project and Game On!