Pokemon Diamond and Pearl! It was a tough battle with Halo 3, but Pokemon actually beat it by a pretty signifficant margin. In 2007, Halo 3 sold roughly 6.4 million copies, whereas Pokemon sold 7.55 million copies in America and Others alone. I didn't bother trying to figure out how much it sold in Japan this year, but I believe it was around 1 million as well. Pokemon Diamond and Pearl is the fastest selling DS game. It has currently sold 13.11 million copies world-wide, and is the second best selling DS game behind Nintendogs at 16.55 million. So, congratulations to Nintendo and Game Freak for making such a wildly successful game!