A weak lineup of new titles meant US video game hardware, software and accessories fell six percent in June to $1.1 billion, according to the NPD Group.
Games sales fell 15 percent to $531 million, thanks to a dearth of major releases, although consoles showed a five percent rise.
"Looking at historical seasonality for the industry, total year US revenues of new physical sales could come in anywhere between $18 and $21 billion," said NPD analyst Anita Frazier.
"Given the strong slate of content still to come, and the release of the Move and Kinect controllers, which I believe will spark additional interest in gaming, I think we could see the total year new physical retail sales come in at $20 billion."
Take-Two Interactive's Red Dead Redemption kept the top slot for the second month running, selling 963,000 copies. It's now the best-selling game of the year so far. Nintendo’s Super Mario Galaxy 2 for the Wii was second, selling 548,400 copies.
Microsoft was the winner in the hardware sector, with Xbox 360 sales rising 88 percent to 451,700 units, thanks to the new Xbox 360 Slim.
Sales of Sony’s PlayStation 3 jumped almost as much to 304,800 units in June, while Nintendo shifted 422,500 Wii consoles, up 16 percent on a year earlier. With fans waiting for the Nintendo 3DS, it's no surprise that sales of the common-or-garden version dropped by a third.
Points and subscription cards - particularly the Xbox Live 1600 points card - were the top-selling accessory type.
Sony took the chance to use the figures to demonstrate that it's finally solved its supply problems.
"PS3 inventory issues have been resolved and June 2010 marks the 11th consecutive month of year on year growth for the platform," it says.