Image & Form have confirmed SteamWorld Dig will release on Steam for PC, Mac and Linux on December 5 at 9 am PST/5 pm GMT.
via N4G: pc news feed http://n4g.com/news/1406393/steamworld-dig-coming-to-steam-december-5
via N4G: pc news feed http://n4g.com/news/1406393/steamworld-dig-coming-to-steam-december-5