

World at War also packs in Zombies: a mode that started as something of a hidden extra but would soon become an increasingly pivotal mode in the franchise. Treyarch delivers Call of Duty: World at War in 2008, a game that sells over 3 million copies in its first two months. The two-year cycle begins and continues quite successfully for a time, with Modern Warfare selling over 7 million copies in 2007 alone. Treyarch previously worked on the 2005 spinoff Call of Duty 2: Big Red One but now, the team is a mainline developer for the franchise. Eager to see these successes not skip another year, Activision brings in one of its internal studios, Treyarch, to develop Call of Duty 3 in time for a 2006 launch.

Notably, there's no new game in 2004: a lone skipped year that has not happened since.Ĭall of Duty 2 is another hit, selling over 1.4 million copies and prompting Infinity Ward to start work on the 2007 entry, Call of Duty 4: Modern Warfare. In preparation for the launch of the Xbox 360, Infinity Ward grows significantly (from around 25 staff members to well over 100) and launches Call of Duty 2 in 2005. It's a World War II shooter developed by Infinity Ward, a studio acquired by publisher Activision after the game's launch is a success. The story begins in 2003 with the first Call of Duty.
