...it is 1975. The cold-war has just morphed into the beginnings of WWIII.
Amidst a 1980's electric guitar peppered soundtrack and the snap, crackle and pop of various machine-gun and cannon sounds you take control of the forces of either NATO or the Warsaw Pact.
It is the game R.U.S.E. could/should have been. By the same developers (Eugen) but no longer published by Ubisoft the game currently has an SP campaign (which is really just a tutorial) and MP (both ranked via ELO and unranked).
The matchmaking is painless and setting up a clan in-game is a just as easy.
They just released patch #4 today and the plan is to patch again soon with MP coop etc. etc.
I come from the days of V for Victory and Close Combat, and while this game is neither as detailed or as slow-paced as those epic series it does have that same sort of "feel" about it. The first time I loaded the game and just sitting at the briefing menu I started thinking "wow.......this is Tom Clancy's Red Storm Rising realised in a videogame".
This is the very first RTS I've ever played that has actually built-in game mechanics that punish single-unit rush [zerg rush] tactics. All units use up fuel and ammo, and if you don't resupply that nice long tank-column you wasted all of your command points on will end up out of fuel in the middle of the huge battlefield and therefore no longer pose much of a threat! 
Any serious RTS fan should check this one out further.......