Awesome game. I beat it on normal. I think that there are a few areas where the juice is masking gameplay issues, but these are relatively minor and expected for something made with so little time to playtest and iterate. For instance, I think that it takes a little too long to kill each Globbin and that the small ones are too difficult to hit; at the same time, the Globbins aren't especially threatening on their own. This means that the ramp-up and ramp-down of each level is a little boring, as the player spends a lot of time kiting a handful of Globbins around without taking them out very quickly either. Furthermore, I think that the different fire modes might be a little unbalanced, that the Globbin sizes should be more unique and distinguishable, that the boss round wasn't very different, and that the control scheme of number keys to switch modes was awkward.
I'm only giving such detailed criticism, though, because the game really earns it. It's worth taking seriously, you know? You did an amazing job. And it looks at a glance like you're a solo developer, too, which makes it even more impressive.