I saw the enemies drop power up when defeated then I was hit with game over screen when collecting it. Then again, that "power up" looks awfully similar with the enemies' bullet.
Anyway, I like shooting in this game. The gun feels powerful. Still, I would prefer if the gun doesn't overheat that fast.
I also saw the gun heat reflected on the enemies' bullet. That's a neat detail.
I kinda expected DOOM-like atmosphere since the protagonist has the "too angry to die" face.