The world’s three-largest games markets – US, UK and Japan – saw an overall 6% decline in video game software unit sales during the third quarter this year, according to a new report from The NPD Group, GfK and Enterbrain.

Top Global Markets, an integrated monthly report from the three research firms, found a healthy software market in Japan, which saw unit sales up by 15% as compared to a 20% dip experienced during the same period in 2008. Console and portable software saw positive unit sales growth, with respective increases of 7% and 19%, though year-to-date sales for its software market experienced a 9% decline.

The UK, meanwhile, saw the largest drop of 19% in unit sales, followed by 9% in the US. Portable game software unit sales were down 34% in the UK, followed by a 12% dip in console software sales. State-side, console and portable game software sales saw declines of 8% and 14%, respectively.

And year-to-date unit sales in the US and UK declined in both console and portable game software, with total unit sales for the US declining by 8% and by 13% in the UK. For sales of kid-friendly titles overall, Nintendo’s Wii Sports Resort came in second and Pokemon Heartgold and Soulsilver ranked fourth.