In the beginning was the void. And then came a boardgame called Civilizations. And then Sid Meier adapted the concept to create one of the most acclaimed video games of all times. The game had descendance and that was good. But it also inspired comptetitors and that was good too.
Call To Power, 1st of the name was a successful implementation of the concept and introduced changes that are not yet present in current versions of the original franchises : new territories ( oceans and space), units fighting in function of their type (shock troops on the front line, ranged units behind, artillery at the back ), clever micromanagement and a different set of marvels.
CTP2 goes even a bit further : newer interface, larger armies, introduction of bonusses for specific achievements. It also dropped the space conquest victory in favour of an ecological victory condition.
Another feature is the ability to implement third mods. Craddle of Civilization or Age of Man might still be available, so do not hesistate !