Get Galactic Civilizations II for Free

Steam News announces the chance to get Galactic Civilizations II: Ultimate Edition for free, following a similar offer from Humble Store last week. Here's word:
Add Galactic Civilizations® II: Ultimate Edition to your account for FREE starting now until Saturday at 10AM Pacific! Once you add the game, it will remain in your account permanently, so don't miss out on this opportunity to own this great title!