Red Dead Redemption: Undead Nightmare is a standalone expansion pack to the 2010 video game Red Dead Redemption. It adds a non-canonical zombie horror-themed single-player campaign, two multiplayer modes, and cosmetic additions to the environments and characters of the open world Western action-adventure game. Set in an alternate timeline from the base game's story, the plot follows returning protagonist John Marston, a former outlaw who sets out to find the cause and possible cure to a zombie plague that has infected his wife and son. Marston liberates towns overrun by the undead and assists non-playable characters with side quests along the way.
