Wow. Just wow. Well done. It's unreal to see stuff like this coming out of a 48 hour jam. I hope you got some sleep at least!
I really enjoyed my time with this game. The art was incredible and really elevated the whole experience. The enemy variety was meaningful and well done, too. My only nitpick would be the first level. I died a few times before being able to upgrade more than one stat. Maybe starting with 2 coins on the screen to let players choose their starting loadout would smooth that over a bit. But once it gets firing, it gets going. I'm not usually a fan of big attack cooldowns, but the basic attack is huge, enemies always die in one hit, and the cooldown is well telegraphed. That's really important. Good job on the design.
Keep making cool games. Be proud of this one. You all rock.