Tribute to the fruit ninja.
wield your devices to cut the fruits in the air, like it is real.
when the game start, you tap the camera icon on the middle of the screen to take a photo , and the app will use this photo of the real world as the AR image to locate the position and the posture of your device, so you can continue playing the game.
the scene had better be static and detail rich when you take the photo. a photo of a white wall will not work.