Nice, you did a great job choosing a scope and sticking to it. I'm not a game designer, but I'll leave some comments below (I'll mention that I played on keyboard):
Good:
- Atmosphere created both through consistent art style and music (always love some classic orchestral)
- Boss fights were fun
- Getting upgrades felt rewarding
To Improve:
- Minimap?
- I found the transition points between screens awkward and jittery, especially when jumping up using the booster jump
- Some of the font text is hard to read
:)