Call of Duty: Black Ops fans have discovered a previously unknown, unfinished Zombies mode hidden in the game's files, more than 15 years after its original 2010 release. YouTuber JTAG found the content while examining a recent PS4 port of the game and shared gameplay footage, offering a rare glimpse into experimental features that never made it to players. The find matters because it sheds light on how much Treyarch tinkered with the Zombies formula behind the scenes, and it may have gone unnoticed indefinitely had the new port not surfaced the leftover files.

The cut mode is a crude, unfinished tower-defence variant in which players could place turrets to hold off waves of undead moving through a maze-like map, viewed from a bird's-eye perspective similar to Bloons Tower Defense, while also being able to drop to ground level and fight enemies directly. It is thought the concept may have been abandoned in favour of Dead Ops Arcade, the twin-stick shooter Easter egg accessible via a secret terminal in Black Ops' main menu, which went on to become a cult favourite and recurring feature in later games. The original Zombies mode itself began as an unofficial side project by a small team using recycled World at War assets, only earning a place in the final game after impressing executives, underlining how much of the beloved mode's history has stemmed from unsanctioned experimentation.