Call of Duty is a video game franchise. The earlier games in the series are set primarily in World War II, but later games like Call of Duty 4: Modern Warfare are set in modern times or in futuristic settings. The most recently announced game, Call of Duty: WWII will return the series to its mid-20th century roots. The Call of Duty series has sold over 250 million copies. Sales of all Call of Duty games topped US$15 billion.