This mod has as goal to recapture the atmosphere and story of SMAC, but create an improved gameplay with the tools offered by Civ4.
An excellent mod! If you liked Alpha Centauri or Civ:Beyond Earth but want something deeper then BE this is a must try. The creators even managed to implement PSY combat from alpha centauri and it's really cool that some units change appearance based on what promotions you pick for them.