I really like how the neon style turned out aswell, I wish I'd had more time to add the things you suggested as they would add alot. I'm going to be taking all the feedback from the jam and releasing a post-jam version with finished mechanics (hopefully) and more enemies and bosses
Making that post-jam version is a good idea, because right now it feels like a crude prototype of something much better it could become. In my opinion this game really needs some kinds of power-ups/upgrades or other clever ways to make you feel like you are progressing. Maybe somehow related to killing the smaller enemies (better upgrades through kill multipliers/drop chances/something else?), because currently there are no incentives to kill them as you can just run past them to the next doorway (those ideas are just off the top of my head).
The overall visuals are really cool, but something needs to be done to the shooting audiovisually. At the current state it just doesn't feel satisfying (imho). You should also consider making the game more fast-paced, because otherwise it can get boring faster due to the lack of content.