Link: steamcommunity.c*om/sharedfiles/filedetails/?id=247032802
Zero-K is a free open-source RTS on Spring Engine, originally start off as a fork (Complete Annihilation) of a fork (Balanced Annihilation) of a fork (Absolute Annihilation) of a balance mod (Uberhack) of Total Annihilation, which is the RTS game that Supreme Commander is based on, so it's no wonder you would see some similarity between Zero-K and SupCom.
But it's still quite a different game, Zero-K is usually played on a smaller scale, it has a bigger focus on physic based unit interactions, projectile dodging is much more common, and all units block friendly fires, but the gameplay isn't overly micro heavy since the game uses a lot of automations. Commander/ACU assassination is not the default victory condition in this game. The economy is simpler, and there is no equivalent of metal maker or moho mine, instead Zero-K uses a system called overdrive, which allow energy structures to boost metal production by connecting metal extractors with a energy grid. There is no tech levels, all structures are accessible to the player from the begining. The factories are ineffective as a build power source, so they are only built when the player needs more unit options, which make building a new factory equal to teching in Zero-K.
Some Zero-K casts by Shadowfury333 if you want a more detailed look of the game:
w*ww.youtube.c*om/watch?v=67pvqdWIaKk
w*ww.youtube.c*om/watch?v=eofK0QvFuUE
w*ww.youtube.c*om/watch?v=SrUWeKryJQM
(remove*, I add them because new users can't post off-site URLs here)