I killed all the enemies on the second level, and I guess that was it? Tough to get the hang of, had some visual effects that the Gameboy wouldn't really have been able to do (notably the explosions), but not a bad start.
Thanks for the feedback. You are right, this is something I realized post submit. I think this is because Godot handles particle effects differently (no snap to pixel transforms).
We very much ran out of time to create content. But thanks for playing anyway!