THQ is giving away free copies of Metro 2033 to fans on Facebook in preparation for the release of its sequel next year, the publisher announced today.

Starting today and running through Dec. 16, fans of the official Metro Facebook page will receive a code for a free copy of the game for Windows PC on Steam, while supplies last.

Based on the book of the same name by Dmitry Glukhovsky, Metro 2033 was released in 2010 and praised by reviewers for the dark and chilling atmosphere it created.

Metro: Last Light, a sequel to the game, but not the book, was recently delayed and is due out for PS3, PC and Xbox 360 early next year.

The game is also currently apart of the Humble THQ Bundle alongside Darksiders, Company of Heroes, its two expansions and Red Faction: Armageddon. Purchasers who paid above the average also received Saints Row: The Third.

Titan Quest, Warhammer 40K: Dawn of War and the Path to War DLC for Red Faction were also recently added to the bundle for those pay above the average.

The pay-what-you-want bundle has just over one day left before it expires and has made over $4.5 million with over 800,000 bundles sold as of this writing.