Call of Duty: Black Ops Cold War is a 2020 first-person shooter game co-developed by Treyarch and Raven Software and published by Activision. It is the seventeenth installment of the Call of Duty series and is the sixth main entry in the Black Ops sub-series, following Call of Duty: Black Ops 4 (2018). Set in 1981, Black Ops Cold War's single-player story follows CIA operative Russell Adler and his team of agents as they hunt down a Soviet spy named Perseus. As with previous Call of Duty titles, the game also includes a multiplayer component and the cooperative Zombies mode. Development on Black Ops Cold War began as a collaboration between Raven and Sledgehammer Games, which was not intended to be an entry in the Black Ops sub-series, but due to disagreements between the two studios, Activision assigned Treyarch as a lead developer on the title in May 2019. Marketing for Black Ops Cold War began in August 2020 and was done in different forms, including cryptic messages within Call of Duty: Warzone, puzzles made to be solved online by fans, and a website showcasing historical Cold War events; a full reveal debuted on August 26, as part of an in-game event in Warzone. The game was released on November 13, 2020, for PlayStation 4, PlayStation 5, Windows, Xbox One, and Xbox Series X/S. Upon release, Black Ops Cold War received generally favorable reviews from critics, and became the best-selling title of 2020 in the United States. Reviewers responded mostly positively to the single-player campaign and Zombies, but were mixed on the game's multiplayer component, with some deeming it to be weaker than the one featured in its direct predecessor, Call of Duty: Modern Warfare (2019). A sequel, titled Call of Duty: Black Ops 6, was released on October 25, 2024.