Actor Nick Swardson attends First-Ever Call of Duty XP at the Stages at Playa Vista on September 3, 2011 in Los Angeles, California.(John Sciulli-Getty Images for Activision)

Actor Nick Swardson attends First-Ever Call of Duty XP at the Stages at Playa Vista on September 3, 2011 in Los Angeles, California.

With more than 100 million units sold and $5 billion in revenue earned, Call of Duty is a mega-entertainment franchise comparable to the likes of Harry Potter or Star Wars.

Those properties have had undeniable effects on pop culture at large. Star Wars lines still get quoted - "these are not the droids you're looking for" - while Harry Potter costumes are a perennial favourite come Halloween time. So, given the video game series' huge commercial success, has Call of Duty had a similar effect?

The people behind the games think so, but pop culture and video game observers aren't so sure.

"It transformed gaming as a whole into something that was more socially acceptable or interesting," says Mark Rubin, executive producer at Infinity Ward, the developer that makes the games. "There were games before it, like everyone knew what Halo was, but it was something kids and college kids did. It didn't really broaden out past that marketplace and if it did, it wasn't vocalized."

Matthew Weise, lead designer at the Singapore-MIT Gambit lab - a joint venture between Singapore's government and the U.S. technology university that analyzes and creates video games - says Call of Duty is a passive phenomenon.

"It's more of a reflection of the current culture rather than something that's fuelling the culture," he said. "If it's in a dance with popular culture, it's following rather than leading."

The military-themed series began in 2003 as a PC game, the first designed by Encino, Calif.-based Infinity Ward. Most of the programmers behind the first-person shooter had previously worked with Medal of Honor, another franchise similarly set in World War II.

The first game, which put players in the shoes of American, British and Russian troops as they battled the Nazis, was a success and won several game-of-the-year awards. It differed from the "lone wolf" approach found in Medal of Honor of games by placing players into large-scale firefights, where they were accompanied by teammates or even large battalions.

Call of Duty 2 expanded the series' popularity in 2005 when it was released for the Xbox 360 as well as the PC. It also put emphasis on online multiplayer combat, which has since become the franchise's main attraction.

By the third game, which was also made available for the PlayStation 3, the franchise had established itself as one of the most bankable in video games. As Eric Hirshberg, chief executive officer of publisher Activision, puts it, the games are successful because of their "epic realism" - or large-scale scenarios that are real enough to be believable, but fantastical enough to inspire awe.

A total of seven main games have been released, with the last few breaking virtually every sales record. According to Activision, at least seven million people are online playing Call of Duty games at any given moment. An eighth iteration, Call of Duty: Modern Warfare 3, is scheduled for Nov. 8 and it's a shoo-in to be one of the biggest games of the year.