When Apple introduced In app purchase as a part of iPhone OS 3.0, developers were allowed to offer in app paid upgrades instead of offering different applications for new functionality.
In app purchase was mainly targeted at developers offering some kind of subscription service or new level packs for games. Developers who wanted to take advantage of this functionality were forced to charge for their applications as a free app could not feature paid upgrades.
On October 15, 2009 Apple extended in app purchase feature to developers offering free app store applications and since then we have witnessed major iPhone game developers taking advantage of this new functionality.
ngmoco:) was one of the first established game publishers to offer their highly anticipated games Eliminate Pro and Touch Pets Dogs absolutely free on App Store while incorporating the in app purchase concept.
Eliminate Pro requires you to have enough energy points to play the game and as you play more often you earn credits. Each time you enter a match your energy drains and can recharge only once a day. If you run out of energy the game allows you still play but no credit points are earned. The credits earned can further be used to buy armor or weapons. To continue winning more credits you will have to win more matches by continually upgrading and staying competitive, which creates an irresistible urge to buy power cells that cost anywhere between $.99 upto $39.99!
Touch Pets Dogs is based on the similar concept but, here instead of buying power cells you have to buy dog food for your pet so that its mood meter stays platinum and you can earn more puppy bucks. You can use the puppy bucks in Pet Store Departments to buy toys, shirts, accessories, career tools, passes and more. If you run out of dog food and your pet is low on energy it will go to sleep, which means you would not be able to play the game or fulfill its career. In order to complete your goals for the puppy and to avoid the long wait you can buy dog food for real money from App Store.
Eliminate Pro climbed the Top Free Apps to take number one position in ten days while Touch Pets Dogs has already reached 52 position in just two days. The strategy adopted by ngmoco:) is very clear, they offered their premium titles which heavily depend on social networking for free and were successful in creating a competitive environment which compels the user to buy upgrades.
No official figures related to the number of users actually buying paid upgrades have been made available yet however, reaching the Top Free Apps category in less than 10 days clearly spells success for ngmoco:)