There’s a lot of VC money going into web-based, advertising-driven casual games, so here’s a wake-up call to investors: They may get better ROI with mobile phone-based gaming.

In 2006, mobile game platform Greystripe launched GameJump.com, a distribution site for free, ad-supported cellphone games; since then, consumers have downloaded over 65 million copies of Greystripe’s hundreds of titles. The company will publish an extended report of their user data later this week, but were nice enough to give me an advance peek. I’m looking at a lot of surprising numbers, but the most striking one to me is how gamers interact with the ads that appear before and after gameplay.

According to Greystripe, 10.1 percent of them click on the ads, a CTR that far outstrips web ads, which average some 1 percent to 2 percent. I strongly suspect at least some of these are accidental, fumble-thumb click-throughs, but even then, from the advertisers’ perspective, that’s not a bug, but a feature. And while mobile games are almost by definition casual, the demographic breakdown is markedly different from the web-based casual space, which is dominated by older women.

By contrast, 69 percent of the site’s U.S. users are aged 18-34, and 60 percent are male — roughly the same percent that own a PS3/360/Wii game console. So unsurprisingly, the top 20 titles are not just puzzle games, but arcade-flavored titles like Rollercoaster Rush and Bikini Pool Summer, from a studio called, appropriately enough, Guy Games. With data like this, I think we’re going to see a lot more money moving to mobile.

Image credit: GameJump.com