Really like the art style and concept!
It seems like it has been said in other comments but I was basically getting shot from off screen by enemies that fire before I can see them, which grew tiring. I tried with keyboard and controller (props for adding controller support!) and couldn't get very far into Level 2 before getting frustrated
I'd also sometimes get unlucky with powerups (run into 2 enemies and the powerup you pick up is a single target one). It would be nice if you could bias toward placing AoE weapons near groups of enemies maybe?
I'd be excited to come back to play this more in the future if you make some tweaks!