That was a really fun time! Kinda reminded me of the necro tank in diep.io if you've ever played that game, which was good as that is one of my favorite ones. I think your swarm was more satisfying to build up than that as it was more fun to recruit enemies you beat.
My swarm felt so powerful by the end of it haha. The chargers hit like a truck are very satisfying to land haha. I also enjoyed the particle effects after the boosts :)
It got a little chaotic after about 100 kills or so and the frame rate dropped a good chunk, but it was still really fun!
Maybe if you wanted to add to more to the game, you could think about another variant of the enemies or maybe make world you and your swarm could traverse where you find different types of enemies in different parts (could feel like fun progression).
Overall, a very fun game and I enjoyed playing!
If you get the chance, I'd love to hear any feedback you have for improvements or constructive criticisms of the game I submitted as I'm trying to get better at this whole process haha