[Spellman]

I thought technically BAR is the OSS heir of Total Annihilation (which then Supreme Commander later developed).

Only 2 sides, no unique Experimental units, etc.

That being said, it's a great FOSS game and really captures the genre feel of epic scale.

[paulddraper]

Yes, Supreme Commander, Beyond All Reason are cousins (and Planetary/Industrial Annihilation) -- all successors to TA.

And there are the direct TA mods...Balanced Annihilation and TA: Escalation

[ffsm8]

Part of that family is also the spring engine (zero-k and others)

[Buttons840]

Each side has unique experimental units, not sure what you mean by that. But, as you say, there are 2 factions to play instead of the 4 you'd find in SupCom. A 3rd faction is being worked on though and can be used in multiplayer, but it's beta quality.