The listing, Guns of Icarus Online - steam key has ended.
http://store.steampowered.com/app/209080/
Hop aboard a steampunk airship with friends and play as Gunner, Engineer, or Pilot. Gun down dirigibles, repair your way out of danger, pilot the ship into combat. Are you a decisive Captain or dutiful Crew? Teamwork is required to survive the skies of the premier airship combat game: GUNS OF ICARUS ONLINE!
Raising the stakes on team-based PvP combat with an emphasis on strategic competition and truly cooperative play, Guns of Icarus Online is the best airship-to-airship combat game that’s all about teamwork, tactics, and fast-paced action. With a good ship and the right crew, you can conquer the skies!