Rain or shine, the Call of Duty must flow. It's a mantra that's served Activision well for 20 years as Call of Duty grew from yet another WW2 shooter to the best-selling franchise of all time.

This is the second year in-a-row that Call of Duty has done this. While the practice has been almost universally praised, Modern Warfare 3's campaign will not be selling anyone on the idea.