I think this game is pretty fun! I think the interpretation on the theme is a *little* iffy, but whatever who cares, this is a good entry.
I like having two upgrade options every level up, and I liked that it is timed, forcing me to try and focus on what the upgrades are and maintain my movement.
I think having to kill enemies in order to get their health is a great incentive to keep shooting and killing them. And having them drop health is a great way to make movement interesting , because I have to decide on the safest option to get that health without just charging into enemies.
I like the sound effects to. Gathering health is really satisfying.
My problems were:
The upgrade sprites are hard to read. I think having some text that names it would benefit it. Short simple names like "SPEED UP!" "MAGNET UP! or something.The projectile sprite moves so fast that at first I had no idea what the upgrade shooting speed did. It looked like a white blob to me cause I didn't recognize it.
There should be some more feedback to the player. This game is already fun as it is to see how long you can last, but enemies just disappear when you die, and it's not entirely clear when I take damage or if I'm low. Some enemy death particles, player damage effects, and some effect to let me know I'm close to death would be really nice.
The other issue is that there isn't any interesting choice with shooting. There's no trade off while shooting, which means there's no reason to not be always holding the shoot button. You might as well have just been shooting automatically, with only having to aim.
Overall, a good and solid entry! I really liked this one!