RedRockRun: Pretty much what the title says. I grew up playing RTS games like Warcraft 2, Starcraft, Age of Empires II, C&C Red Alert et. al.
Yet whenever I look through the strategy games, I mostly find strategic/tactical RPG's or space strategy games along the lines of Homeworld. What I'm looking for are base-building RTS's like the ones I listed above. So far, I'm thinking about getting Cossacks, but other than that, I'm not aware of any big titles.
I'll think of some more, but right of the bat I can tell you of an incredibly bad-ass series : Dawn of War set in the Warhammer 40k universe. Dawn of War 2 had most of the base building stripped out (still an awesome game imo) but Dawn of War 1 has a strong base building element (though not nearly as strong as Starcraft/ CnC or Agies)
There was the original, then Winter Assault and finally Dark Crusade (there was another sequel after that which I don't count : series reached it peak with Dark Crusade which I also think is the best of the three on its own). I mean in what other game do you have this :
http://www.youtube.com/watch?v=aKHsj5y8UL8 and THIS :
http://www.youtube.com/watch?v=MRiU2N03Rzs edit : ignore the weird warcraft the music the uploader chose for that sequence in the first link - its not the ingame music, and doesn't do it any justice
EDIT 2 : Ok here is another title that is not that well know, but that is actually very good :
http://www.mobygames.com/game/act-of-war-direct-action Its kind of somewhere between CnC and World in Conflict with very satisfying combat.
Another : [url=http://en.wikipedia.org/wiki/The_Lord_of_the_Rings:_The_Battle_for_Middle-earth]http://en.wikipedia.org/wiki/The_Lord_of_the_Rings:_The_Battle_for_Middle-earth[/url]
If you are at all a fan of the LotR movies, then this game is a must. Unorthodox base building, but base building nonetheless. The game is pure awesome, you can defend/attack Helm's Deep and Minas Tirith depending on what side you are playing, and you can send hordes of orcs flying with Gandalf's word of power spell :
http://www.youtube.com/watch?v=flCV1z01G78 As for the titles on GOG that I know a little bit of:
KKND : Very funny game, in a mad max esque universe. Very satisfying combat but can be obscenely difficult, up to the point you get snipers/crazy harrys at which point it becomes fairly easy.
KKND2 : I enjoyed it, but I thought KKND was better.
Dark Reign : Similar era as KKND, and probably the better game but also tough as nails (or it was when I last played it as a kid). Also : kick ass fmv sequences
Empire Earth : Brilliant game, especially the skirmishes. Even though the AI cheats horribly, it is very novel to start in the stone age and play your way up to giant mechs.
Empire Earth 2 : Don't bother imo...
Battle Realms : I've only heard good things about this
Earth 2160 : Uhm yes well, this is a monster of a game. Massive tech trees, complex bases and a unit creator ingame.
Total Annihilation : Probably the greatest/ most legendary RTS game on gog
MAX 2 : From what I've heard : completely and utterly inferior to the first MAX, which I played to death. MAX is an awesome game, but it is turn-based.