I have installed the Planetary Pack but when I load the game, it only shows Alpha Centauri.

Am I supposed to load some other files to play Crossfire?

OK. Found the answer in a thread on the second page and apparently you need to open terranx.exe and that does work.I was using GOG Galaxy which doesn't seem to be able to open Crossfire.

In the SMAC page on GOG galaxy, look under "more" (to the right of the play button) and then "other", and if your instalation was correct, you will find "run alien crossfie" as an option.

That''s true! It's almost as though Alen Crossfire is a last minute thing, not a "separate" game. But it's easier to launch Alien Crossfire here than it is to launch Rome Total War - Barbarian Invasion on Steam. (Which btw is a game I'd like so see here on GOG!)

I have Sid Meier's Alpha Centauri & Sid Meier's Alien Crossfire. However when I play the Alien Crossfire there are no faction of Aliens? Please help.

There was something that made that happen in my games a long time ago.... i cannot remember what exactly caused it, but i was using the scenario editor, and that had something to do with it.

I played around for a while and figured it out.... sorry i dont remember what i did, but its solvable!