Call of Duty is a first-person shooter video game franchise. The series began on Microsoft Windows, and later expanded to consoles and handhelds. Several spin-off games have been released. The earlier games in the series are set primarily in World War II, including Call of Duty, Call of Duty 2, and Call of Duty 3. Beginning with Call of Duty 4: Modern Warfare, which is set in modern times, the series has shifted focus away from World War II. Modern Warfare, released November 2007, was followed by World at War and Modern Warfare 2. Black Ops, released November 2010, takes place in the Cold War, while Modern Warfare 3, released November 2011, takes place in a near-future setting. Black Ops II, released November 2012, takes place mainly in the year 2025. Call of Duty: Ghosts was released in November 2013. In May 2014, Advanced Warfare was announced. On April 9, 2015, Treyarch announced Black Ops III.
The Call of Duty games are published and owned by Activision. While Infinity Ward is still a developer, Treyarch and Sledgehammer Games also develop several of the titles with the release of the studios’ games alternating with each other. Some games have been developed by Gray Matter Interactive, Nokia, Exakt Entertainment, Spark Unlimited, Amaze Entertainment, n-Space, Aspyr, Rebellion Developments, Ideaworks Game Studio, and nStigate Games. The games use a variety of engines, including the id Tech 3, the Treyarch NGL, and the IW engine.