I really like how the numbers concept encourages more strategy in kiting and enemy priority (and it's a fun reference to Doki's legendarily bad grasp of numbers in general). I think it could be tweaked to be deeper, but for a game jam it's solid, I think!
I agree with some other comments here: the "ouch" sound being compressed is extremely funny, the big score amounts are satisfying (as is seeing a big chain pop off), I found one music track a little grating (could be my speakers!), and clicking to fire every bullet is kind of tiring, and a possible accessibility issue.
I think some of the visual communication could be handled a bit better. It's a little hard to parse enemy hit counters when they begin to swarm, and it's also a little less "instinct-based" trying to focus on the number on the enemy instead of something such as the shape or color. I also think that making the weaker enemies faster would mean a player had to make a bunch of different tactical decisions instead of one decision repeatedly (chip away at the big numbers till they're low enough to be set off by each other with a shot). I also could have used some more Doki references, but I appreciate that it's more difficult in this type of game than in (say) a visual novel, where you can reference something by just writing another line of dialogue.
If you decide to keep working on this one after the jam, I'd welcome the opportunity to play it again and see what you cook.