The two studios' input has been "beneficial," according to Infinity Ward's creative strategist.
Unlike previous games in the series, which have been solely the work of Infinity Ward, Modern Warfare 3 is a co-production with two other Activision studios: Raven Software and Sledgehammer Games. But rather than have three very separate teams working on three very separate elements of the game, Infinity Ward's Robert Bowling says that they're working much more closely together.
Bowling said that the situation was more like the three studios were one big team, rather than three smaller ones, with everyone working on the same tasks. It's co-development across the board," he said. "There's never been a clear divide of 'this is yours, this is ours, don't touch this, don't touch that'. It's across the board of playing to each other's strengths and weaknesses."
He said that Raven was helping in the same way it had assisted Treyarch with Black Ops: providing extra bodies to do "random UI and engineering tasks." Sledgehammer, which Bowling said had a very different background to the other two studios, had contributed to the game's storytelling, as well as how the team did things. Bowling said that Sledgehammer's input and fresh perspective had been "beneficial" to the project.
As beneficial as it may be, it's likely that this collaboration wouldn't have been necessary had the dispute between Activision and Infinity Ward co-founders Jason West and Vince Zampella not happened. Activision fired West and Zampella for insubordination, and the pair subsequently set up Respawn Entertainment. A few dozen Infinity Ward staff members then jumped ship to the new studio, leaving the old studio understaffed. Of course, if it ends up reinvigorating the series, then the cloud may very well have a silver lining.
Call of Duty: Modern Warfare 3 comes out for PC, PS3, and Xbox 360 on November 8th.