In anticipation of the NPD Group's monthly sales estimates, Sony has announced that PlayStation 3 exclusive shooter Killzone 2 has sold more than 1 million copies worldwide.

An official statement from the company gloats that "the hit game has garnered the biggest initial success at retail of any first-party PS3 title to date, and will continue to drive incentive for hardware sales throughout the year."

Sony Computer Entertainment's Scott Steinberg said earlier this month that the Guerilla Games developed Killzone 2 has "exceeded our expectations." The title sold more than 500,000 copies in the U.S. in its first two months on the market.

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