Although a bit basic, this was a pretty fun and simple shooter game! There's a reason lots of games use a similar upgrade system as yours does, and that's because it's satisfying, which stays true here as well.

Obviously there's always room for improvement in game jam titles, especially in jams as short as this one, but if I could give just one suggestion, I'd say giving more feedback to the player when they do different actions (like shoot or throw bombs) is crucial. It often felt like I hadn't even hit an enemy because there were no hit effects. And these don't have to be anything flashy, even just a few small particles flying around or a satisfying sound effect can do the trick.