Love this game. I probably played more of this than Civ 2 back in the day, and still load it from time to time. More than I ever played of Civ4 or even the original Colonization, and I played them a lot as well. It was quirky, a bit hard to get into, but then it was so cool once you'd got used to the research trees, colony building and unit design. And the wonders were so cool. Slightly unbalanced in a few ways (esp the new factions and some wonders), but there was always a foil for most things. Except helicopters, but that was pretty standard for civ games back then. Loved the factions and how far you could change your empire around with different ethics, loved the various styles of victory, loved the extreme feeling of power it gave you at the higher tech levels. Global economic superpower with mega-nukes and alien wave attacks? Can be done. None of the Civ games gave you this feeling of superiority at the end game, but you had to work to get there as well. Which was more rewarding than chariot victories or 2-settler starts every time. Although, pod drops and monoliths could seriously change the game in SMAC (although, so did barbarian villages in Civ).
From memory it was pretty moddable on the factions/techs/etc. Have any decent mods been made for SMAC/SMAX? Either balancing mods or just extra content. I remember fiddling with the factions a fair bit back in the day, which changes things a lot, so surely someone else did something similar?