According to the analysts at NPD, overall video games sales fell over 4 percent in January 2011 when compared with the same month a year earlier, with slowing hardware sales weighing heaviest. The firm reports that retail video game hardware, software, and accessory sales generated $1.36 billion in the month.

Of the three segments, only accessories gained year over year, and NPD credits this turnaround to strong sales of Microsoft's Kinect add-on for the Xbox 360 and Sony's Move add-on for the PlayStation 3. Both devices provide some measure of Nintendo Wii-like motion-sensing capabilities to the respective consoles.

Video game console sales dropped 8.4 percent in the month to $324 million, however, while software sales dipped 5.1 percent to $576 million. Accessory sales finished at $235.1 million, up 5.5 percent year over year.

Although NPD no longer provides individual console sales figures to the press, Microsoft, Sony, and Nintendo often release those figures independently. So far, only Microsoft has done so: It says the Xbox 360 was the best-selling console in January, with 381,000 units sold, up 14 percent year over year, and the only console to experience growth over that time frame. According to various sources, the Nintendo Wii finished in second place, with 319,000 units sold (down 31 percent), followed by the Sony PlayStation 3, with 267,000 units sold (down 3 percent).

The bestselling game title, for the third month in a row, was Activision's Call of Duty: Black Ops (360, PS3, Wii, PC), with more than 750,000 units sold. This was followed by Just Dance 2 (Wii), Dead Space 2 (360, PS3, PC), Little Big Planet 2 (PS3), and Zumba Fitness: Join the Party (360, PS3, Wii).

In related news, Microsoft is reportedly holding a "core games" event this week in San Francisco. And separately, Microsoft has quit the PC Gaming Alliance, a non-profit consortium that was formed in 2008 to promote the PC gaming industry. No reason for the departure is currently available.