Black Ops 2, released in 2012 by Treyarch, expanded the Zombies mode that had become a defining part of Call of Duty, with players surviving waves of undead on maps like Tranzit and Die Rise. Its eerie audio, from groans to ambient dread, helped make the mode feel distinct from the main shooter campaign. Years later, clips from the mode still circulate in gaming edits, reaction videos and Halloween content because that sound instantly signals danger, survival and classic zombie horror to fans.