To unlock the hidden game (Easter egg) on Android KitKat powered devices, go to Settings and tap “Android version” several times. A big “K” will appear on the screen. Press down on this to launch a KitKat chocolate-bar style logo, and then press down on this to launch the game.
Older versions of Android also have Easter eggs that you can access by following the same way. For example, on Ice Cream sandwich devices, you will get an animation of flying Android logos wearing ice cream sandwiches.