How exactly does this work? I thought that once a Steam game is tied to your account, It's there for good.
certain games were given away on the x-mas sale for comopleting select achievements as well as coupons for games. you can also buy games as gifts and use them as tradeable goods.
for example you could buy say CSS as a gift and then trade it away.
i had won 5 free games this holiday season i won:
red alert 3
gemini rue
CSS
portal 2
and finally HL2: ep2
i have since redeemed them or given them to friends/family
i also got a whole piles of coupons for hard reset, shadowgrounds, valve games, AvP (2010), and some others..
should have been there getting steam goodies was sooooo easy!
valve did a miracle this year.. they gave away so much free stuff its incredible. they do this again next year and get the word out more, steam would cause a mass console migration to pc.
was almost as awesome as the following: