Pretty darn fun! Feels fun to rack up a big number of hits and then use earthquake as a finisher - game feel is great. My only real gripes are - it feels like spamming it a bit too effective, I know it probably won't rack up as much score but just in general it feels pressing one button (and occasionally a second) is an effective strategy that makes my carpal tunnel ridden hands sad. That and I do wish there was more to it - I understand that it is a Jam game so I very much understand time constraints and I'm requesting for a full on campaign but this does feel a lot more like a tech demo for a larger game or like a "proof of concept". Again, I'm not discrediting the work that was done to make this, be proud of that, I'm simply relaying that it was good and I was excited to see it twist/turn in some way as it went on and it kind of just didn't (though the boss was a nice shakeup!)
My much much more minor gripe is: having a functioning online scoreboard but NOT a volume slider - those explosion sfx layering on top of each can get pretty violent!
Overall VERY well made and I sort of hope you expand upon the concept more in the future! Would be cool to see this as a fully fleshed out game!