"Not a hard decision, but a long decision," Rubin said. "We don't get a chance when making a game to think about the next one until we are done actually making that first game."

"So when we finished Modern Warfare 3, we had this big brainstorming session that lasted for weeks," he added. "Everybody gets to come up with ideas of what we want to do, not just what game we want to do, but moments in games."

Rubin explained that the entire studio knew it wanted to continuing making Call of Duty games, even though it could have made something else. He said the team wanted to build a new universe, with new characters and experiences.

"The easy thing would have been--as we had finished the arc of Modern Warfare 1, 2 and 3--to start a new arc within that same universe. That was the first step," Rubin said. "But due to a lot of the changes we wanted to make with this new world, it really dictated out that we needed to make something that wasn't Modern Warfare."

The result is Call of Duty: Ghosts, the latest entry in the hit shooter series and one that is being billed as having a more emotional storyline. Infinity Ward has tapped Academy Award-winning Traffic and Syriana author Stephen Gaghan to write the game's script.

Call of Duty: Ghosts will launch later this year for Xbox 360, PlayStation 3, and PC, as well as Xbox One and PlayStation 4.