PLEASE READ: This app is a demo for Unity developers. If you don't know what Unity is, please don't download this app. This app cannot be used to make your phone immersive entirely.
This app demonstrates the Immersive Mode plugin for the Unity Engine. The plugin allows Unity developers to hide the navigation bar (soft key buttons) on Android devices, so that their games can run full-screen. You can get the plugin here: https://www.assetstore.unity3d.com/#/content/16852
If you're a Unity developer, and you have any questions about this plugin, feel free to send me an email. You can also discuss it on the forum: http://forum.unity3d.com/threads/244659-RELEASED-Immersive-Mode-for-Android?p=1618183#post1618183