German developer Fishlabs is rapidly becoming the place to go to get your mobile advertorial games made.

Most recently it was behind the Brawn GP Racing iPhone game (which significantly wasn't free), as well as the Volkswagen Polo Challenge, which as a free app did 350,000 downloads in six days.

Now however Waterslide Extreme - a game based on Barclaycard's 'iconic' waterslide advert - has been downloaded more than 2 million times within a week.

Apparently it's "dominated the global download charts" and is currently the number 1 free app in 57 countries, including America, the UK, Germany, Canada, France, Spain and Japan.

"We had high expectations regarding Waterslide Extreme based on our throughout positive experiences with ad games," explains Michael Schade, Fishlabs' CEO.

"With over 16 million engagement minutes to date and thousands of reviews, interest in the waterslide campaign has really peaked again and we are thrilled," says Paul Troy, Head of Advertising and Sponsorship, Barclaycard, UK.

So it seems we should expect more of this sort of thing on the App Store. Least we're not paying for it yet.