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The "mostly single-player" DLC features a new campaign following Redemption's hero John Marston as he searches for the cure for the "highly infectious zombie plague" that has infected the Wild West. Along with undead humans, Marston will have to contend with zombified animals lurking throughout the frontier -- like a giant freakin' bear.
According to the short, debut trailer, Undead Nightmare will launch "very soon." The content will be made available on the PlayStation 3 and Xbox 360 for $10 (800MS Points).