Are you familiar at all with Warhammer 40k? The Dawn of War series is a excellent RTS set in the 40k universe following a chapter of Space Marines known as the Blood Ravens. Standard RTS fare but with fun grimdark stories. The original games were pretty standard, Dawn of War 2 was a large step up in production and story telling, though the RTS moved away from base building and towards small squad control. The expansions went back towards Base Building.
Relic also handled the Space Marine game if you're familiar with that at all. It's just an action game in the universe is all, and no Blood Ravens.