I enjoyed this one a lot, it was fun to mix and match the upgrades.
I found the idea of multiple guns confusing, do they all fire at the same time? Or were there more buttons I was missing. I couldn't tell if there was a balance to the amount of guns I should have vs having fewer, other than dispersing upgrades.
The wireframe art is excellent and I appreciate the accurate Bresenham lines that most people miss.
As a final note: The arenas always felt too tight to me, maybe shrink the enemies or give a bigger play area.