This was a really good submission! A lot to it, and done really well! I think a few tiny tweaks could make it even better though - one of them being having a health bar so I could see how long I had - and the other is to just buff the numbers a lot more. Don't give me a 10% increase in bullets, give me 100% increase!
I want every upgrade to be an event where the gameplay really ramps up, rather than just a slow gradual thing - especially for a jam game when people are only going to be playing for a few minutes, by the end I think it feels best if they're godlike by that time.