http://zero-k.info/
(It also has a single-player campaign where you slowly get to learn the more than 100 units and features.)
But BAR/Spring seems like it would fit you better (it's also the closest of them to TA, which is otherwise a bit old these days) :
https://www.beyondallreason.info/
(BAR used to stand for Balanced Annihilation Reloaded, while Zero-K used to be called Complete Annihilation.)