I'm not usually into idle/idle-ish games, but something about this one was very entrancing. I don't know if it was the slowly-spinning screen, the high-contrast colours, or the gameplay (which was a little more involved than a Cookie-Clicker clone or a sit-back-and-watch type game), but I kept wanting to do one more round!
I enjoyed the skill-tree-like store, too! Though maybe you could've shown (but kept locked) a few upgrades farther down the "branch," rather than just the next one. It might be nice to have something greater to work towards, and give the player a little more agency.
This last bit of feedback is very subjective, but as a jam game, it might've been better if the upgrades were a little more substantial, and we became over-powered sooner. If this were a mobile game you expected ppl to play for hours on the subway to and from work, than these kinds of increments might be good or maybe even a little too substantial. But in a jam, you want players to feel everything they WILL feel relatively quickly! And it took a while for me to hit that "hell yeah!" feeling. But I don't know what your aspirations for this game are. There's certainly potential to turn this into a full-fledged idle game—mobile and/or otherwise—if you wanted!