Red Dead Redemption: Undead Nightmare

Red Dead Redemption: Undead Nightmare is a 2010 action-adventure game developed by Rockstar San Diego and published by Rockstar Games. A standalone expansion pack for the open world Western game Red Dead Redemption, it adds a non-canonical, horror–themed single-player campaign, two multiplayer modes, and cosmetic additions to the environments and characters. 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 of and possible cure for 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.