Valve has finally made refunds possible for all Steam games.
The new refunds system allows players to return any game within 14 days of purchase as long as they've played it for less than 2 hours.
The new refunds policy applies to game and applications but not to movies and streaming video. It applies to some DLC, but not all of it. More specifically, any items or DLC which irreversibly upgrade game characters cannot be refunded. Such items will be clearly marked on Steam as being nonrefundable. Also, getting banned for cheating in game would make it ineligible for refund.
Before the new policy, Valve handled refund requests on a case by case basis. On the other side of the fence, Origin Great Game Guarantee program has been allowing EA Origin users to return no-questions-asked refund within 7 days of purchase for nearly 2 years now.
More info on Steam refunds program can be found here.
