How I made the ants in my game
I wanted the ants to be upgradable with visual changes, a 3D model seemed the easiest way to do this because I can just attach objects to the animated model later without having to worry about doing any extra work.
So I made this model, running in the background
Then draw that to a 2D texture and apply this texture to all the ants. Because the model is rendered only in one place it doesn't cost much in performance

An early stress test. There's not much left of all the detail but it did the trick

You can play the game here: https://ldjam.com/events/ludum-dare/46/antourage