Beyond boring corporate sales figures and the often-unreasoning acclamation of fanaticism, there's one simple way to define a classic videogame: when you refer to a new game as "like X meets Y", X and Y are probably classics [are those prequels to Z? -'funny' ed.]. So consider Stardock's Brad Wardell telling us "Ashes of the Singularity is like Total Annihilation meets Company of Heroes meets Kohan", or our old Nathan declaring "Planetary Annihilation is like Total Annihilation with planets." The conclusion? Total Annihilation is a classic. The 1997 RTS has lived on GOG and other digital stores for ages, but has only now touched down on Steam.
Total Annihilation brought vast swarms armies of robotic mechs, vehicles, aircraft, tanks and naval vessels. I remember being impressed by units taking cover behind trees (I swear this was impressive at the time) and being wary of the fact that entire forests could be set alight with a single stray shot. I remember its strikingly realistic sort-of-3D landscapes (again, for the time) and symphonic score. I was a fan, in case you hadn't gathered. Did I mention it's a classic?
After developers Cavedog Entertainment closed, members went on to work on sprawling, TA-referencing RTSs like Supreme Commander and the aforementioned Planetary Annihilation.