Scandinavian mobile ad start-up Didmo is gearing up to take on the likes of Greystripe in the ad-wrapped mobile game market. Sort of.

Didmo's platform wraps mobile games in an "ad-supported shell." Consumers can download the games and play them for free for 24 hours, according to GameDaily.com. With Greystripe, which pioneered the concept, users can keep on playing the games they've downloaded, with the system automatically refreshing the ads on a predetermined basis.

GameDaily reports that Didmo is now branching out into the U.S., U.K., Germany and Spain. According to the article, Didmo's ads see a click-through rate that's some 500% higher than for traditional WAP ads.