• by Gavin O'Malley  @mp_gavin, July 13, 2009

Call them co-brainers or light entertainers, casual games continue to account for a larger share of consumers' time online, according to new data from comScore.

Ostensibly driven by tighter household budgets, the category attracted 87 million U.S. visitors in May 2009 -- up a healthy 22% year-over-year.

Yahoo Games ranked No. 1 in the category with 19.4 million visitors in May, representing a 6% increase over the past year, followed by the fast gaining EA Online with 18 million visitors -- up 34%.

Nickelodeon Casual Games drew 14.8 million visitors in May, while the WildTangent Network attracted some 13.8 million visitors during the month.

GSN Games Networks, meanwhile, achieved particularly strong gains in the past year, growing 563% to 6 million visitors, due primarily to the additions of entities such as WorldWinner.com and CrazyMonkeyGames.com.

"Online gaming continues to be one of the top gaining categories over the past year growing at ten times the rate of the total U.S. Internet population and reaching nearly one out of every two Internet users," said Edward Hunter, comScore director of gaming solutions. "And the growth in the category is occurring not only at the top gaming destination sites, but also through viral distribution platforms, including widgets and applications. In fact, some online gaming companies that distributed their games across sites are reaching as many people as the top online gaming sites." Distributed content, as measured by comScore Extended Web Metrix, represents a growing trend in the online gaming space.

Distributed content platforms, including widgets and applications, can often reach audiences of a size comparable to online gaming destination sites. MochiMedia, for example, 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 twenty sites in the category, while Tetris Online reached 165,000 people.

"The power and reach of viral content distribution is well captured by comScore Extended Web Metrix," said Alok Kejriwal, co-founder and CEO of Games2win. "With these latest consumer traffic numbers, we can now effectively present and strategically leverage our accelerating audience reach, and share data with our adve rtisers, marketers and partners that represents a holistic view of who is playing our games and from where."