Sid Meier's Alpha Centauri (SMAC) was a very interesting title. It came about because Sid Meier lost his rights to the Civilization franchise for a period of time. Yet SMAC was considered the real successor to CivII rather than Civilization Call To Power because of the recognition and the genius of Sid Meier.

But SMAC was in its day quite divisive. Some Civ fans (self included) weren't able to get into the world with unfamiliar tech tree, obscure terrain features and the whole nomenclature of the game just being so... alien.

Now, granted it was likely the best sci-fi turn based title ever made but at the time us fans of Sid's work were really craving for a sequel to CivII and as a result SMAC received a somewhat lukewarm welcome. Likely undeservedly so.