It's a fun game, I like the procedural levels and the progression on upgrades is pretty nice.
Small improvements I'd make:
- UI could be more readable, the font is weird and you're thrown into the game without much time to look at things or figure out what's what.
- Some screenshake would go a long way, though I understand if you're going more for Vampire Survivors-like with minimal juice to distract from the progression.
- The directional audio feels very weird, it always sounded off so as not to be useful. I think the power of the guns would feel better if it was removed altogether.
- Perhaps a pause screen when you walk over a gun so you can decide what to swap it with. You could even compare stats, fire rate, ammo type, etc. I suggest this because the only two times I died was when I tried to pick up a gun but couldn't determine when to press F and also was trying to switch to a gun I didn't want.
- Reloading takes way too long. I think you're trying to encourage the player to switch weapons, but the arenas are so big and it's so easy to strafe around enemies that I'd rather wait on the reload than change my concentration to which weapon would be better.
You got a good base here though, keep it going.