Blacks Ops 2, the latest in the blockbuster Call of Duty shooting game franchise, has registered more than $1 billion of global sales, a feat that Activision said was accomplished on the game title's first 15 days of commercial availability.

It was no mean feat for the latest of the gaming line that has successfully surpassed the gross ticket sales of Hollywood hits in 2012, said Activision Blizzard chief executive Bobby Kotick said in a statement released on Wednesday.

In fact, "life-to-date sales for the Call of Duty franchise have exceeded worldwide theatrical box office receipts for 'Harry Potter' and 'Star Wars', the two most successful movie franchises of all time," Mr Kotick added.

In a separate statement, Activision Publishing chief Eric Hirshberg labelled the impressive result as "an incredible milestone for an incredible franchise."

"Call of Duty remains the entertainment juggernaut that it is ... (because) we continue to bring fresh ideas and new innovations to the table every time ... That's what we did with Call of Duty: Black Ops 2, and that's what we intend to keep on doing," Mr Hirshberg said.

To underscore the incredible run currently enjoyed by Black Ops 2, Activision compared its sales performance to another hit game, its sibling Modern Warfare 3 that also pocketed $1billon shortly after it hit store shelved worldwide but only after 16 days.

Another point of reference is the landmark movie of James Cameron, The Avatar, which attracted ticket buys of $1 billion during its initial 17 days of screening in cinemas around the world, Activision said.

Gaming industry watchers, however, have expressed fears that COD has already peaked despite indications that the franchise has maintained its popularity among gamers in different parts of the world.

According to Yahoo gaming blog Plugged-In, Black Ops 2 already clocked 150 million of gaming hours since it was rolled out, which is roughly equivalent to over 17,000 years of gaming - solid proof enough that the game title has gained considerable inroads in the global gaming community.

Yet based on the monitoring of Sterne Agee & Leach, "unit sales of Call of Duty: Black Ops 2 are tracking down double digits year over year."

"The current sales curve suggests CoD: Black Ops 2 unit sales in its first year could ultimately be down 10 per cent to 15 per cent year over year. If we are right, this would be the second year in a row this critical franchise will have seen units decline," Sterne Agee & Leach analyst Arvind Bhatia.

One solid plateau indicator is how Black Ops 2 is faring in the United Kingdom, where "it hasn't managed to match the sales of previous games in the gargantuan first-person shooter series," EuroGamer.net reported.

On that part of the world, Black Ops 2 is only number four in terms of the number of copies that were snapped up by English gamers on the first week of availability. The top distinction belongs to the original Black Ops, which EuroGamer.net said sold some two million copies seven days after its debut.

The new COD title also failed to dislodge Modern Warfare 3 and Modern Warfare 2 from their sweet spot, respectively occupying the number two and the number three slots.