Most iPhone apps do not come with warnings - but Doodle Jump, the #2 paid application by Lima Sky, has built an advertising campaign around the addictive gameplay: Be warned: this game is insanely addictive!" The ad unit then cycles through anonymous iTunes reviews that highlight just how addictive the game is. Once clicked, the ads take you directly into iTunes so that you can download Doodle Jump for $0.99 and spend hours draining your iPhone's battery!
