Call of Duty: Black Ops set new records for sales at its debut last November, making it the world’s most popular video game. Can Call of Duty keep growing as a franchise?

That’s a big question, as Activision Blizzard hopes to top Black Ops with the November 8 launch of Call of Duty: Modern Warfare 3. If fans keep flocking to the game, Activision Blizzard can make another billion dollars in revenue from the series. This year, the game faces tougher competition from Electronic Arts’ Battlefield 3, which debuts October 26.

Jamie Berger, vice president of digital at Activision Publishing, a division of Activision Blizzard, believes that growth is still possible. Today, roughly 20 million unique monthly users are still playing Black Ops, especially the multiplayer version, more than 10 months after the launch. More than 30 million have played this year, and more than 18 million map packs have been sold for Black Ops. Collectively, fans have played for 2.3 billion hours.

Berger said the audience is still growing as the number of high-definition consoles (Xbox 360 and PlayStation 3) sold has risen considerably since last year. The company feels its Call of Duty Elite social network will make the game even more appealing, and the awareness of the franchise keeps growing.

“Call of Duty has now become a phenomenon on an annual basis,” he says. “We’ve got a terrific story for consumers.”

Check out our video interview with Berger at the Call of Duty XP fan event in Los Angeles.