When you're building a free app, consider how you plan to earn revenue, whether it's through the support of other apps from your company, support of your brand, via ads, or any combination of all three. In this section, you learn how to add required elements to turn your app into a revenue-generating machine, beginning with absolutely free apps.
From a business perspective, regardless of which revenue model you pursue, the key factor in a free app is user engagement. Engagement is an important term for any app or game on any platform, but is especially poignant with regard to free apps.
Let's say you're supporting your app via ads. Every time your users use the app and come to one of your ad's landing spots, whether it's on the core gameplay screen or in between screens, one ad gets served. With high engagement (meaning that you have a base of users who frequently use the app on a regular basis), the ads are served that many more times.
When you combine high engagement with short session requirements (meaning that users aren't required to play for more than 5 minutes at a time), the formula becomes a winning combination. The ads are being served much more frequently.
Consider “Angry Birds” as an example. In between each loading screen, you have ads for other Rovio software, or supporting fan pages for the brand. Because each level takes from 30 seconds to 5 minutes to try, users are seeing a great number of ads.
The same ...