Call of Duty Zombies began as a survival mode in Call of Duty: World at War, where players held off endless waves of undead in round-based matches, and it grew into a part of the Black Ops games. The round start cue became a familiar marker for players, signalling that the next wave was about to spawn and the map would get harder. As gameplay clips and montages spread on video platforms, creators reused the sting to frame their runs, and it remains popular because it signals a new challenge to anyone who has played the mode.