In fact, Stern considered the villains of Modern Warfare to be one of the strong points of the overall story. "We had Zakhaev in Russia and Al-Asad in the Middle East," Stern says. "We wanted to present the alliance, how they were involved together and all the double-crossing that was going on and the ultimate ambitions - what they were trying to accomplish. They weren't the canned madmen trying to kill a bunch of people. You want to keep your bad guys smart. They have an agenda that motivates them.
"One of the things I pushed for was to get more story into that opening scene. Zakhaev gives Al-Asad the gun, and he's complicit. They animated that sweet thing where he swings the gun. I remember seeing that and thinking, Goddamn, these guys are so good. I kiss their ass an awful lot, but I think it's warranted."
Two games into the series, the developers at Infinity Ward have proven themselves masters of playing with its audience's fears about global conflict. "We've had some conversations that were scary as hell," Stern says. "Last summer there was one where we talked about some Russian guys starting a war in the former Soviet Republic over an oil pipeline. A week later, and tanks are rolling into Georgia. We were like, 'Huh, that's bizarre.' Then we had a conversation about something that would be really terrifying: guys with grenades and machine guns taking out soft targets in a major metropolitan area. We were talking about doing it somewhere in Asia, and then Mumbai happened. We looked at each other like, 'Is anyone else a little worried?'
"We were tapped into a strange kind of thinking. We wanted to keep it modern, keep it with contemporary fears, but also look just slightly into the future. Like, what's the next scenario that scares the crap out of everybody?"
Shocking players turned out to be the easy part. A bigger challenge was drawing the stories to a satisfying conclusion. "From the very beginning, the biggest issue we had was the ending," Stern said. "We'd talk about that, but we'd keep tabling it." Modern Warfare 2 has been called 'the Citizen Kane of shooting people in the face,' but in the original Modern Warfare's final moments, you can't help but feel it's about more than just that. You have a bond with your team after all you've been through, and to see them executed while you lay there utterly helpless is gutting. You see the gun slide across to you, and it's cinematic and emotional - but most of all, it feels real.
"At the end of Call of Duty 4 you forget about the politics, you forget about whatever it's all about: It's just two guys on a bridge trying to kill each other." And ultimately, that might be the story's greatest success: In a game filled with tanks, choppers and nuclear warheads, it's still the characters that have the biggest impact.
Jack Baldwin is an international man of mystery. He is also a freelance contributor to The Escapist and enjoys writing poems about ham on weekends.