Activision Blizzard, the Santa Monica-based publisher of the blockbuster video game 'Call of Duty: Modern Warfare 2', said in a January 13 announcement that its internal estimates have revealed that the worldwide retail sales of the November-launched game has surpassed the enviable $1 billion mark.

The estimated figures disclosed by Activision indicate that the new game is apparently well on its way to beat the 2007 sales record of 14.4 million units sold of 'Call of Duty: Modern Warfare' - thus far the best-selling title in the immensely popular six-year-old 'Call of Duty' franchise.

On the basis of the recently-released estimated sales figures of the game, 'Modern Warfare 2' currently ranks among the all time best-seller video games, including the most recent versions of the Grand Theft Auto and Super Mario series.

Activision further said that, going by the estimates, the first five days post-release global receipts figures for 'Modern Warfare 2' stood at $550 million; thereby clearly beating the first-five-days worldwide theatrical box office gross figures for films like Avatar, Harry Potter and the Half-Blood Prince and The Dark Night.

Though the publisher stopped short of specifying the exact number of 'Modern Warfare 2' units sold in the first week, its generation of $550 million in receipts indicates that the first-week sales of the game were almost 15 million.