It's the biggest lie that there is "server upgrade and service will be recovered in couple of days" or something like that. Unless it is constant server upgrade.
The best 4X combat. Huge variety of units and sides (need DLCs though). Unique game in that it just focuses on combat, no diplomacy (it sux in all games anyway) no spies (also sux in other games), and simple but reasonably good (and different for different races) economy. It focuses at one thing - combat, drives it to perfection and the rest of the game design narrow focused to support that.
Being W40K helps with richness of the fluff, if this is important for you.
That reminds me about the music of Leonardo Workshop world’s miracle in Civ 2. I remember very little about Civ 2, but this wonder is with me forever:)