While Apple is particularly careful not to let any skill-based gaming features - i.e. winning real things by playing games - to pass through the App Store's hallowed portal, that doesn't mean cunning developers aren't layering competitions onto their games external to their apps.
The best example so far has been Upstream's complex competition for the Brawn GP Racing game which will see one lucky punter win a Mercedes SL Roadster.
Obviously operating on a much smaller scale, London-start up FIPLAB has something similar to encourage you to buy its CopterKid game.
Once 5000 scores have been submitted on the game's global leaderboard, the top placed player will win $150, the second $100 and the third $50.
Registration is fairly easy: you just have to enter a username and an email address from within the app. I'd suggest that winning any cash might be harder, however, as the highest score is already 20x what I could manage, although I am only ranked 34th globally.
CopterKid is now available for 99c or 59p - a offer limited to its first 20 days. Hit the 'Buy It!' button to go directly to the App Store.