Marathon Infinity takes the closed universe of the Marathon series and blows it wide open. The solo/co-op campaign, “Blood Tides of Lh’owon,” is a 20-level scenario sporting new textures, weapons, and aliens. More than that, the scenario sheds a surprising new light on the story’s characters and the meaning of events. Having defeated the Pfhor and reawakened the ancient remnants of the S’pht, the player now faces a world where friends become enemies and all is not what it seems…