I'm not really seeing what this game has to do with metroidvania, but to be fair I did die like a dozen fights in and didn't feel like replaying it. Despite that, I am really enjoying it. I think you should have gone with that "shooter without being able to stop shooting" description as the main point, instead of the metroidvania first. But if I missed something because I didn't play it enough, let me know, and I'll give it another try.
As a top down shooter where you just point to shoot, it is fun. It got tense when my health was low and those smaller enemies were shooting a lot at me. Good work.