If you bought an early US copy of the action adventure game Darksiders, then you may just have a little treat waiting inside the box.

You see, publishers of Darksiders THQ put a little redemption coupon inside Xbox 360 and PS3 copies of the game that was marked with the words “Do Not Discard,” and owners were instructed to visit the Darksiders website to wait and see what the coupon was for.

A month later, we get to see what it does.

Well, if you meet the above criteria (you bought an early, initial run US version of Darksiders and still have the game and its contents, including the coupon), and you live in the US, you are now entitled to a free copy of THQ’s excellent Red Faction: Guerrilla.

All you need to do is visit this Darksiders blog post and redeem your code!

You’ll also be able to get a “digital Hellbook disc featuring Darksiders art, videos, and other awesome stuff!”

Also note that this offer expires on March 7th this year, and shipping and handling of your free copy of Red Faction: Guerrilla is not included in the deal…