In what's clearly a lesson of how to get it right as far as apps that advertise go, Barclaycard's "waterslide" iPhone game has seen 3 million downloads in just 13 days.

The app, that supports Barclaycard's current ad that sees an office worker sliding down a water tube picking up items with a swipe and pay Barclaycard, is now said to be the most popular free branded advertising game in the history of the iTunes App Store.

The game, created by Dare and Fishlabs, is now the number one free iPhone application in 57 countries.