online-game-sitesThe number of online game players rose 22 percent in May compared to a year ago, drawing more than 87 million players in the U.S., according to market researcher comScore.

That improvement is a stark contrast to the slide in overall console game revenues in the U.S., which fell 23 percent compared to a year ago in dollar sales, according to market researcher NPD.

The comScore analysis showed that gamers are increasingly opting for cheap entertainment alternatives, driven by the recession. Some analysts are expecting console games to post a 20 percent drop in game sales in June, compared to a year ago. Later in the year, a rebound is expected. NPD numbers for June console sales will be out on July 16.

Yahoo Games ranked No. 1 in the category with 19.4 million visitors (up 6 percent from a year ago), or roughly 22 percent of the online game market in May. It was followed by EA online with 18 million visitors, up 34 percent from a year ago, Nickelodeon Casual Games with 14.8 million visitors, and WildTangent Network with 13.8 milli0n visitors, up 16 percent.

GSN Games Networks grew 563 percent to 6 million visitors, thanks to the addition of partners and Online games are growing at 10 times the rate of the overall U.S. Internet population, said Edward Hunter, comScore director of gaming solutions. The category is expanding both through the growth of web sites and through the growth of widgets that allow games to be distributed across a variety of sites.

Viral distribution of games (where a company’s game appears on numerous different sites) is catching on. MochiMedia reached a combined audience of 16.9 million in May, greater than all but two sites in the online gaming category. Games2Win reached 1.8 million people, which compares favorably with the top 20 sites in the category, while Tetris Online reached 165,000 people.