According to data compiled by Xbox Live's director of programming, Larry "Major Nelson" Hryb, Black Ops beat out the likes of Halo: Reach, Red Dead: Redemption, and Battlefield: Bad Company 2 to secure the top spot.
Nelson formed the list by compiling the number of unique users logged in each game's first seven days. This strays from the lists posted in 2008 and 2009, which displayed a full year's worth of data.
Nelson defended his methodology by saying, "I did the first seven days since that is a way to normalize the data and give all games a fair chance."
Read more of "Black Ops is Xbox Live's top game of 2010," and see the other top titles, at GameSpot.