The game competition is as tough as it gets, with Grand Theft Auto ruling the market, and breaking some of Halo 3’s records. But yes, there is room for more, as Infinity Ward confirmed that Call of Duty 4: Modern Warfare has sold 10 million copies.

Infinity Ward’s Vince Zampella told CNET News he wasn’t familiar with the exact number of units sold on each of the three platforms (Xbox 360, Playstation 3 and PC), but according to his estimations, the Xbox 360 has been the most successful for Call of Duty 4.

Now that the 10 million mark has been reached, the question is: will they be able to deliver another 10-million hit in the future? Zampella wasn’t too sure about that either, saying that Infinity Ward will have a hard time releasing another best-seller such as this one.

Call of Duty on Nintendo? No way, said Zampella, adding that Infinity Ward took the decision not to make the game for Nintendo Wii simply because “it doesn’t fit the Wii” and releasing it for that platform would compromise the game.

Furthermore, Zampella suggested that the game will not stop here this year, especially in the holiday season. By the end of the year, Zampella expects the game to sell even more copies, adding approximately 1.5 million more to the 10 million units sold.

Call of Duty 4: Modern Warfare is the fourth installment of the Call of Duty video game series, and in 2007 made it to the top-selling games list. The game is a first-person shooter, and unlike its predecessors, the action is set in present days.