SMAC was what Sid (and company) did when he left his original company and went off on his own. It was a civilization-like game that was basically set "after the people of earth got to Alpha Centauri".
SMAC was non-historical and contained signfiicant plot elements that explained the strange world you ended up on. They put in the kitchen sink in many cases, and would add features even if they knew the AI couldn't exploit them at all effectively, so long as it made the game interesting. After all, you can always ramp up the AI's ability to cheat to deal with that kind of tactical hole.
So you had planet-busters that changed the terrain, significant terraforming, spies that bought cities, water cities, space satalites that sent resources down to your planet.
The AI was set up to "role play" their faction in a reasonably convincing manner -- it was set up so that you
knew why you where at war with a faction: because of ideological differences, not because of blind grasping for power.
Because it was set on an alien world with future technology, a lot of the suspension of disbelief problems go away: your leaders do live for centuries, because you have the technology.
I'm a big Hive fan (and a Plannet Cult fan). I also love the terrain graphics in the pic. Looks fantastic. 
