The PC industry isn’t the only one that had a rough time over the holiday quarter. Per VentureBeat, the latest data from the NPD Group show that video game hardware and software sales in the United States totaled $3.2 billion at retail last month, a 22% decline from the $4.1 billion the industry posted in December 2011. One big culprit in the decline has been the rise of online stores such as Valve’s Steam that give users an alternative to trudging down to their local GameStops to buy new games. As far as hardware sales go, NPD found that Microsoft’s (MSFT) Xbox 360 remained the best-selling console in December, selling 1.4 million units, followed by Nintendo’s (NTDOY) 3DS at 1.25 million units. Ominously for Nintendo, the company’s new Wii U console sold just 460,000 units on the quarter, less than the original Wii’s 475,000 units.