Ah, an RTS. An eerily familiar one, as outside this jam I'm also working on a game with swarm-based battles. So I'm definitely one to enjoy this sort of ongoing battle constantly going on in the background. The units look really good, and it's fun to watch them duke it out.
If there was one thing to improve design-wise, I feel like the economy would be one. Right now building a large army seems essentially free, resources aren't a factor, you just need to wait a little. Although maybe that's not 100% accurate, as the levels seem to use building space as a resource. It sometimes works at the very beginning, where you need to win the first battle to place more buildings, but it's not really a concern later.
I like what the "next stage" button becomes at the very end 😄 And it's cool how you came up with different sounds for ordering different types of units around.