AC is actually a 'sequel' to the Civ universe
I am a huge fan of CIV III, and bought the previous incarnations of it as well... in fact I was about to buy it for my new puter when I read that Civ 4 is coming out this year. I actually preferred Civ 3 to alpha centauri. I liked to play at the harder levels on civ, but with the minimum number of opponents. That way I have time to build something up thats worth defending before I run into opponents (of course the opponents have the same advantage)... with my strategy I am always outnumbered in terms of military units, but in terms of technology I am dominant... That usually carries the day...
Nothing I have seen in gaming so far beats the suspense of planning a MASSIVE (D-DAY Times 10) assult on a heavily armed opponent....