Enebias: Sid Meier's Alpha Centauri. I think that game is still the best 4X ever created: 7 believable factions with solid ideologies behind them, a wise use of both in-game characters and real human literature quotations, technological trees based on hard science, always changing maps and AI strategy (once they tried to drown my cities by melting the polar caps! They increased the sea level by 333 meters! THAT'S MONSTROUS!), terraforming, customizeable units, advancend city and economics management and an unmatched replay value. Sometimes it really made me think of how hard could be to run a country, given all the unpredictable events and reactions. Plus, you can play as the ultimate fascist-communist immortal leader: how could you ask for more? ;)
The problem with Alpha Centauri is the enduring disappointment it creates for me over every other similar game i have played year after year that fail to improve on it. And this is despite the fact that games are supposedly supposed to improve over time.... Bah humbug!
I mean, what is it going to take, it's been 14 years already and I'm still waiting!!!!!!!!!!!!!!