Probably the juiciest and most-polished entry I've played yet, fantastic job. Everything is reactive and built with so much care and attention toward game feel. This feels like a game that would already do well as-is on mobile or other casual platforms.
Was hard to pull myself away from "just one more round" to come leave some feedback. Reaching for things to criticize or suggest and try to provide something constructive to improve...
I felt like there could stand to be a bit more differentiation beyond the splat sprite between dealing damage to an enemy and killing one, especially early on as you're trying to get a feel for the mechanics and which things to prioritize. It gets so chaotic visually, especially later on, that I'm not sure how you'd make it clearer when things actually died amid all the chaos, but I think it might be a bit helpful for the player to contextualize what's going on. Maybe could be fun to add a mechanic where the player can tap/click on an already-placed ball once it slows down to get it going again once per round or something like that? Yeah, I'm really struggling to think of much to improve this!
Phenomenal work!