Activision Blizzard said that the fan reaction to the initial disclosure about its upcoming Call of Duty: Black Ops II video game suggests it will be the biggest game in the history of the franchise.

That’s a big expectation, considering that last year’s Call of Duty: Modern Warfare 3 was a huge hit. But pre-orders for Black Ops 2, a sequel in terms of storyline to 2010’s Call of Duty: Black Ops, have set new records, the company said in an analyst call today.

With Black Ops II, Activision studio Treyarch has taken some big risks. The studio has shifted most of the story for the game into the future, in the year 2025, where the U.S. gets embroiled in a second Cold War (this time with China) and fights battles with drones and robots. The game features advanced weaponry that is either already in the hands of today’s superpowers or is being prototyped.

“Black Ops II is hands-down our most ambitious Call of Duty game to date,” said Eric Hirsberg, chief executive of Activision Publishing, said in a conference call. “The team is challenging assumptions on every front: the single player campaign, multiplayer, facial animation and graphics technology.”

Activision Blizzard has a huge, ongoing audience for Call of Duty, since players continue to play the multiplayer version of the games long after they’ve finished the single-player campaigns. Hirshberg said on a call with analysts that Call of Duty has 40 million monthly active players, well above the 30 million the company mentioned last year.

Players have played 2 billion online game sessions for Modern Warfare 3, up 19 percent from the hours played in the same time frame versus Call of Duty: Black Ops from 2010. With Modern Warfare 3, Activision launched a gamer social network, Call of Duty Elite. More than 10 million have registered for it, and 2 million have opted to get the premium version, which costs $49.99 a year. Engagement with Elite has been increasing since January, and it has released on multiple screens including PC, console and mobile.

Call of Duty Black Ops 2 is expected to set new benchmarks in “quality, immersion, innovation, and great gameplay,” said Bobby Kotick, chief executive of Activision Blizzard, in the conference call.

He added, “We believe it has the potential to be the best Call of Duty ever.”

Modern Warfare 3 apparently didn’t outsell Black Ops from last year, partly due to the impact of revenue recognition for Call of Duty Elite and lower revenues from a la carte downloads of Call of Duty map packs.

As for the online version of Modern Warfare 3, the activity is still strong. Kotick said the company continues to work on an online-only version of Call of Duty for the Chinese market.

“The performance of Call of Duty online continues to be stellar,” said Thomas Tippl, chief operating officer of Activision Blizzard. He said he does not anticipate changes to the company’s policy of releasing Call of Duty multiplayer content on Xbox Live before it does on other platforms. Kotick said that he expects Activision Blizzard to have a record year in revenues in 2012.

Hirshberg said players have created more than 800,000 clans for multiplayer game play.