Sid Meier's Alpha Centauri (SMAC) is the critically acclaimed science fiction turn-based strategy video game sequel to the Civilization series. Sid Meier, designer of Civilization, and Brian Reynolds, designer of Civilization II, developed Alpha Centauri after they left MicroProse to join the newly created developer Firaxis Games. Electronic Arts released both SMAC and its expansion, Sid Meier's Alien Crossfire (SMAX), in 1999. In the following year, Aspyr Media and Loki Software ported both titles over to Mac OS Linux.
Set in the 22nd century, the game begins as seven competing ideological factions land on the planet Chiron ("Planet") in the Alpha Centauri star system. As the game progresses, Planet's growing sentience becomes a formidable obstacle to the human colonists. Alpha Centauri features improvements on Civilization II's game engine, including simultaneous multiplay, social engineering, climate, customizable units, alien native life, additional diplomatic and spy options, additional ways to win, and greater mod-ability. Alien Crossfire introduces five new human and two non-human factions as well as additional technologies, facilities, secret projects, native life, unit abilities and a victory condition.
The game received wide critical acclaim, being compared favorably to Civilization II. Critics praised its science fiction storyline (comparing the plot to works by Stanley Kubrick, Frank Herbert, Arthur C. Clarke and Isaac Asimov), the in-game writing, the voice acting, the user-created custom units, and the depth of the technology tree. SMAC also won several awards for best game of the year and best strategy game of the year. However, despite the good reception, the game had the lowest sales of the Civilization series.