Re:SteamOS: It's here
by leoc on Friday December 13, 2013 @08:28PM
(#6904072)
I know one person who bought the wrong game on Steam by mistake: he couldn't get a refund but he was able to persuade Steam support to add the value of the purchase to his Steam wallet.
Nonetheless, this seems to be a good place to mention GOG's 30 day money back guarantee: http://www.gog.com/support/website_help/money_back_guarantee