You're not going to believe what the most popular games on Xbox Live were in 2011. OK, maybe you'll believe it. According to Microsoft's count of worldwide unique users for the year, Call of Duty: Black Ops topped the list of retail titles, followed by Modern Warfares 3 and 2, Halo Reach, and Battlefield 3.

On the Arcade side, the top seller was Pinball FX 2, followed by Full House Poker, Castle Crashers (which came out in 2008), Fruit Ninja Kinect, and From Dust. Beyond Good & Evil HD hit #20 on the list, which seems good, but too close for comfort, for those of us hoping it would be a strong indicator of interest in the sequel.

You can find full top twenty lists for retail, arcade, and XBLIG, along with Games for Windows Live and Windows Phone (Surprise! Angry Birds!) at Major Nelson's blog.