The tileset you made is awesome, and I like that the levels have multiple paths and can be navigated using whatever powerup you choose to pick. The controls feel good, the combat was a little bit slow in my opinion (enemies took too many hits to die).
I agree with the door comment, and I think there was also a turret enemy that was kinda camouflaged into the background.
Other than that, this is a short but great platformer and the ending cutscene is very nice. Good job!