Really, really great gameplay concept here, and it definitely fit the limitation. I will say that, after respawning a few times, knowing the pathways from before kinda reduced the need to shoot bullets to find my way. If you decided to iterate on this concept, I think randomly generated levels would be a way to go to avoid that. Music and sounds were really great, and the atmosphere was perfect. Sometimes simple art is the way to go, and you nailed it here. Awesome work!