Command & Conquer-style games? Well here are a few suggestions:
Command & Conquer
Command & Conquer - The Covert Operations (Expansion pack for Command & Conquer)
Command & Conquer Tiberian Sun
Command & Conquer Tiberian Sun †“ Firestorm (Expansion pack for Tiberian Sun)
Command & Conquer Red Alert
Command & Conquer Red Alert - Counterstrike (Expansion pack for Red Alert)
Command & Conquer Red Alert - The Aftermath (Expansion pack for Red Alert)
(These ones are still good to play.)
Command & Conquer Red Alert 2
Command & Conquer Red Alert 2 †“ Yuriâ₠¬Ã¢â€žÂ¢s Revenge (Expansion pack for Red Alert 2)
(These are a bit cartoony but good fun)
Command & Conquer Renegade (more a FPS really)
Command & Conquer Generals
Command & Conquer Generals: Zero Hour
(Excellent games - still play them regularly)
Dune 2000 (Made by Westwood †“ similar to Command & Conquer)
Emperor †“ Battle For Dune
Total Annihilation (Robots vs robots)
Z: Steel Soldiers (Quite high tech)
S.W.I.N.E. (Pigs vs rabbits - I kid you not)
Earth 2150
WW3: Black Gold
Ground Control
Ground Control II
(Not played either of these all that much but they look good)
Giants: Citizens Of Kabuto (stretching it a bit, but does have a kind of RTS side to it)
"The Settlers" series of games
Real War
Real War: Rogue States (expansion pack for Real War)
(USA vs the Commies and moderately authentic)
Starcraft
(I think, but not too sure about this one - not played it yet. Hugely popular in Korea.)
Maybe the "Age Of Empires" series too
Patrician 1 & 2
Anno 1503
Apart from that, I can't think of any! 