Really interesting weapon system, and feels just like an old cartridge! Unfortunately, I ran into a bug on stage 2: every time I respawned, the game spawned me inside the floor, preventing me from getting any further.
Sorry about the bug. I think it's to do with the system the game uses to push you back to playable space if you get crushed by a wall; I'll try to fix it when I can. Other than that, I'm glad you like the weapon system!