Overall U.S. video game sales fell 13 percent in January to $1.17 billion, according to market researcher NPD.

Game hardware sales fell 21 percent to $353.7 million, driven by both so-so sales in January and higher hardware prices a year ago. Software sales were down 12 percent to $597.9 million, and accessories were up 2 percent to $217 million.

As we reported last month, December sales were up only 4 percent from a year earlier, and for all of 2009, game sales were down 8 percent.

Nintendo maintained its lead in hardware sales. The Wii sold 465,800 units, while the Nintendo DS and DSi handhelds sold 422,200 units. The Xbox 360 sold 332,800 units, while Sony brought up the rear with 276,900 PlayStation 3s sold, 100,100 PlayStation Portables sold, and 41,600 PS 2s sold.

One of the big sellers of the month was Mass Effect 2, which Electronic Arts said earlier had sold 2 million units in its first week. In the U.S., NPD said Mass Effect 2 sold 572,000 units on the Xbox 360 (the game didn’t go on sale until Jan. 26). The No. 1 game of the month was the New Super Mario Bros. for the Wii. That game sold 656,600 units.

There were five Nintendo Wii games in the top ten, four Xbox 360 games, and one PS 3 game (The PS 3 version of Call of Duty Modern Warfare 2). Microsoft says Mass Effect 2 is off to a great start and that other big titles coming are Halo: Reach (in the fall, with a multiplayer beta starting in May), Alan Wake in May, and Crackdown 2 in June [Microsoft’s update: it made a mistake, and isn’t announcing a Crackdown 2 date yet].

Peter Dille, senior vice president of marketing at Sony’s U.S. game division, said in an interview that demand is strong for the PS 3 but the company didn’t have enough consoles on store shelves this month. Since demand began to pick up with the launch of the PS 3 Slim in August, Sony has had to play catch up on getting enough consoles into stores, he said. On top of that, more of Sony’s big titles are coming later. Heavy Rain, released today for the PS 3, is getting strong reviews. And God of War III arrives in March. Sony released MAG, a shooter game with up to 128 players in a match, on Jan. 26. That game is selling well, Dille said.