It gets great when you get good upgrades, I just had an amazing run with 92 kills thanks to extra damage explosive shotgun shots.
A lot of the upgrades seemed to do nothing, the opposite, or something random entirely, which i'm guessing is supposed to be the theme connection. It didn't really work in gameplay though, it just felt like the game was buggy or lying to me. I think to really make the theme work there needs to be an understanding of how things go wrong, not just things randomly going wrong. An example of how to do this would having explosive shots deal damage to yourself if you're too close to enemies.
Also you say you used "some audio" from Pixabay, would that include the music or did you make it yourself?