If zombies are more your thing, you can download The Walking Dead: Season Two for free between April 16th and May 15th on Xbox One. For Xbox 360 users, Darksiders and Assassin's Creed: Revelations will both be available to grab at no cost. Darksiders will be available April 1-15 while you can get this particular installment of Assassin's Creed from April 16-30. Of course, thanks to backwards compatibility on the Xbox One, those two 360 titles will be available to current-gen console owners as well.