The fuel thing on the left was weird and the thing with X/20 fuel collected suggested they were optional but you cant complete the levels with them. Other than those two things the game was really good.

Pacing is really nice for the project, you've got the level design flow down to a tee. Only thing I would say that was misleading was the objective - Since you have a fuel gauge at one side of the screen, I assumed I had a limited resource that only refilled when the pickup was collected (Rather than it being the resource to unlock the ship). Making it something different like a piece of the ship, an artefact, coordinates would've reduced early confusion in game. Great work.