This is a fun little game, well done! There's groundwork here for some pretty cool stuff and it all plays very well. Nice job!
A few of the upgrades felt underwhelming, especially the absorption radius upgrade. I liked the ammo/mana pool, though I wasn't sure what the bar at the top left of the screen was? Experience? I'm unsure I leveled up outside of getting the checkpoints and weapons. The shotgun felt the best. I got the laser later and, while powerful, it didn't feel nearly as good as the shotgun.
The boss took me by surprise. He looked so different with the lighter color palette and the bubble asking for food that I thought he was a friendly. Boy was I wrong. Got through it on the first go though!
I think for a jam game, it dragged on a little long. It was mostly the same thing over and over until eventually a boss.
Overall, well done! Congrats on finishing the jam :)