Activision's first-person shooter video game franchise is celebrating its 20th anniversary in October  the first Call of Duty game hit PCs in October 2003. Its latest entry, Call of Duty: Modern Warfare III, arrives Nov. 10 for Microsoft and Sony game consoles and PCs.

Call of Duty (2003): This is the first game in the series and sets the stage for the franchise. Call of Duty 2 (2005): This game is a direct sequel to the original Call of Duty and is set during World War II.