A worthy addition to the--Name of Sid Meier--family of games
The additional complexity of the diplomatic aspect of the game, the addition of psi combat, the customization of military units from a workshop all add to the game. In addition, the AI is much improved over Civ2, although not perfect.
The menu system is much too complex, you *will* learn the keystroke commands for the most frequently used actions. There isn't a Mac version -- many of my friends use Macs.
The Bottom Line
I would call it Civ3 in space. If you didn't like Civ, you won't like Alpha Centauri. If you did like Civ or Civ2 and a science fiction theme doesn't bother you, you will love AC.