After initially proving resilient in the economic downturn, sales of videogame hardware, software, and accessories have suffered six straight monthly declines in the U.S.—pointing to a difficult struggle ahead as game companies prepare for the critical holiday shopping season.

Microsoft Corp., Nintendo of America, and Sony Computer Entertainment America have all cut prices on their consoles in recent weeks as part of the natural life cycle of videogame hardware. That promises to help overall unit sales during the holiday season, but the lower prices could still translate into reduced revenue in the end.

Overall, videogames promise to fare better than many other sectors over the holidays, but analysts say the industry will still feel the effects of the tough economy.

“An awful lot of merchandise is still going to go out retailer doors this holiday season, because videogames are still at the top of many kids’ wish lists,” said Michael Goodman, an independent videogame consultant in Boston. “But maybe instead of getting two games, you only get one game. Or instead of getting a peripheral, you just get a game. Those are the kinds of decisions I think parents are going to be making.”

The direction of the overall industry has significant implications for the Seattle region, which includes Microsoft’s Xbox and game divisions, Nintendo’s American headquarters, and many independent game developers. A 2007 study by the Washington Interactive Network found more than 15,000 videogame-related jobs in the region and more than 150 companies or divisions involved in games.

Through August, total 2009 sales of videogame software, hardware, and accessories were $9.07 billion in the U.S.—down 14 percent from the same period last year, according to the market-research firm NPD Group.

Rather than taking lots of big risks on new franchises, game publishers and console makers are leaning heavily on new adaptations of tried-and-true titles—tapping into well-established audiences. Nintendo, for example, will release New Super Mario Bros. Wii on November 15, updating the venerable game for the Wii console and its motion-sensitive controller.

Nintendo is billing it as the first Mario game with a true multiplayer mode. Cammie Dunaway, Nintendo of America’s executive vice president of sales and marketing, said the company hopes the game will appeal to new gamers, potentially lifting sales of the Wii, but also to experienced gamers who already own one of the Nintendo consoles. “It’s one of these Nintendo games that operates on multiple levels,” Dunaway said.

Other key titles coming from Nintendo include Wii Fit Plus, due out October 4, a new version of the software for its pressure-sensitive Wii Balance Board accessory.