The economy may be trending downward, but video-game software and hardware sales in the U.S. keep going up. Game sales are up 37 percent over the same time last year, according to the NPD Group, a leading market-research firm. Hardware sales are up 34 percent.

Projected as High as $23 Billion

On Thursday, NPD said video-game sales in May were about $1.1 billion, bringing total sales for this year so far to about $6.6 billion. NPD projected that 2008 games sales could go as high as $23 billion. In 2007, games sales were $18 billion, an increase of more than 40 percent over 2006.

A boost in overall sales came from the fourth installment of the most recent title in the Grand Theft Auto franchise, whose Microsoft Xbox 360 version has been the best-selling game for two months. It sold 1.3 million units in May, for a total of 4.2 million since it came out in April.

Total hardware sales reached $428 million. In fact, there was substantial improvement in sales, year-over-year, in every category, including accessories. In order, the hardware rankings for May were the Wii, Nintendo DS, PlayStation 3, Xbox 360, and PlayStation Portable.

Top Video Games

Take-Two Interactive's GTA IV fought off stiff competition from two new popular releases, Mario Kart and the exercise game Wii Fit, both for Nintendo's popular Wii console.

In fact, the Wii and its Nintendo cousin, the handheld DS, had seven of the top 10 game titles for May.

GTA IV for the PS3 was fourth, after the Xbox 360 GTA IV, Mario Kart, and Wii Fit, and was followed by Wii Play with Remote, Wii Super Smash Bros: Brawl, PS2 Iron Man, Wii Guitar Hero III: Legends of Rock, NDS Pokemon Mystery Dungeon: Explorers of Darkness Noa, and NDS Pokemon Mystery Dungeon: Explorers of Time Noa.

NPD indicated, however, that, even though GTA IV sold about 871,000 units for the Xbox 360 and about 443,000 for the PS3, its success was not greatly helping the sales of either platform.

The research firm added that hardware sales may yet get a boost from two seasonal occasions in June — graduations and, in a possible blow to tie-makers everywhere, Father's Day.

According to NPD, Nintendo sold about 675,000 Wii game consoles in May, compared to about 209,000 for the PS3 and about 187,000 Xbox 360s. These figures bring Wii sales to about 10.2 million so far.

Sony hopes the new Metal Solid Gear 4, which has just come out and is a PS3 exclusive, can help it sell more game consoles. MSG 4 is the final chapter in that franchise, which stretches back nearly 20 years.

Nintendo's DS placed second in unit sales, with about 452,000 sold. This is the fourth consecutive month that the Wii and the DS have taken the top two hardware positions. The Xbox 360 just barely beat the PlayStation Portable in hardware sales.