Ok, reposting this as Aydrian’s thread has gone walkiesand no, I don’t have the expansion….yet 
http://www.firaxis.com/smac/game.cfm
One of the greatest strategy games of all time. There’s a few errors in the portable version as it’s my first attempt at making a game portable so i’ve included a non-portable version at the bottom for if you get irritated by them.
Legendary designer Sid Meier presents the next evolution in strategy games, with the most addictive, compelling gameplay yet. Explore the alien planet that is your new home and uncover its myriad mysteries. Discover over 75 extraordinary technologies. Build over 60 base upgrades and large-scale secret projects for your empire. Conquer your enemies with a war machine that you design from over 32,000 possible unit types.
Portable Features
*No install or CDKey required! Just click and play.
*Only one single executable and a folder that saves important stuff so there isn’t any clutter.
*Completely portable! You can put it on a USB drive and play it anywhere.
Intro Video
http://www.youtube.com/watch?v=035cpHEowS4
PortableDownload- (100MB links)
http://rapidshare.com/files/198889825/Sid_Meier_s_Alpha_Centauri-WBB.zip.001
http://rapidshare.com/files/198889829/Sid_Meier_s_Alpha_Centauri-WBB.zip.002
http://rapidshare.com/files/198901191/Sid_Meier_s_Alpha_Centauri-WBB.zip.003
http://rapidshare.com/files/198901194/Sid_Meier_s_Alpha_Centauri-WBB.zip.004
Known Errors and Solutions (with the portable version):
*When you start up the game it’ll complain about the lack of CD.
Just hit cancel and it allows you "limited" gameplay, I’ve still yet to find what’s limited about it, possibly because it’s a copy of a full install, which pulls all the files off the CD.
*If like me you get two boxes on launching the game with nothing on them, hit the left one, it may just be a vista issue as it did the same before i made it portable .
Alternatively you can download the iso version from these links if that annoys you/you don’t really want to carry it about on your USB
ISODownload- (200MB links)
http://rapidshare.com/files/200312995/Sid_Meier_s_Alpha_Centauri.part1.rar
http://rapidshare.com/files/200316668/Sid_Meier_s_Alpha_Centauri.part2.rar
My first upload on WBB after several months of leeching (if you don’t count the post on Aydrian’s portable game thead, where’s that gone btw? I lived on there )
The ISO was downloaded from somewhere else originally, and that’s what I created the portable version from, but I can’t for the life of me find it to credit itIf it’s you, you know who you are