There are more than 500 people, across four or five studios, keeping the Call of Duty franchise running on a yearly schedule. It appears that keeping the franchise annualized isn't as simple as one studio takes the helm every year, with the ball previously bouncing between Treyarch and Infinity Ward. This year's installment, Modern Warfare 3, required cross-studio assistance, following the implosion of developer Infinity Ward.
Although some may not be fond of mega teams, Activision has a good friend in super-sized development clusters with Ubisoft. Over 400 folks were needed for Assassin's Creed 2 and that number hasn't violently shifted as the franchise annualized, delivering the stellar Brotherhood the following year and Revelations this fall.