I loved Alpha Centari. It was another Sid game released around the time of Civ 2. It plays just like civ, except you are rebulding man kind as the leader of one of seven factions. The Alian Cross Fire expantion gave you seven more factions to choose from (encluding 2 Alian factions), but the game always used seven factions. I love that you could build a "custom" faction that enable you to start at the top of the tech tree while everybody started at the bottom. Yes, it was cheating, but some time you get frustated when you keep getting beat that you just want to make the game pay for it.