Ubisoft's Assassin's Creed series has hit 20 million lifetime sales.
The milestone follows the highly successful launch of third title Assassin's Creed: Brotherhood last week, which the publisher's EMEA chief of marketing and sales claims has already sold over a million copies in Europe.
"It's the best launch in the history of Ubisoft's European sales," Geoffroy Sardin told MCV, "and our best-selling launch title ever."
Sardin believes the franchise will reach 30 million by the end of next year, on the eve of a planned fourth game's release.
He partially attributed Brotherhood's launch week success - coming in at only 63,000 units shy of Black Ops' second week sales - to its multiplayer mode.
"Apart from the big marketing campaign that we started a few week ago, and which continues over the coming weeks, the main reason the game has succeeded is that we transformed the brand from a single player one to a multiplayer one," he said.
The publisher's data revealed 60 per cent of the game's purchasers had tried the hide'n'seek-based online modes.
A number of DLC packs are also planned.