Here they are:

https://github.com/beyond-all-reason/Beyond-All-Reason

https://github.com/ZeroK-RTS/Zero-K

I can't recommend Zero-K enough. It plays like a dream. Super fun at all levels. Great 8v8 clashes of robots. Unbeatable price ($0). Great dev blogs.

https://store.steampowered.com/app/334920/ZeroK/