From now until July 5th
PC gamers always feel good buying from GOG.com, as there's no Steam/Origin/other DRM login verification prior to playing your games. Today (June 18th) they launched their "2013 #NoDRM Summer Sale" that will be live until July 5th.
Over 500 DRM free PC downloads will be on sale with new hot offers refreshed daily on their homepage. For the first 48 hours they're offering RPG game Torchlight for free - a solid start to their sale.