This quick tutorial will show you how to build a game for Mobile VR and covers everything you need to know about how to turn your phone into an immersive Virtual Reality experience. Also covers the basics of setting up a Bluetooth Controller.
Google Cardboard: https://www.google.com/get/cardboard/
Google Cardboard SDK: https://developers.google.com/cardboard/overview
You can watch Part 2 here: https://www.youtube.com/watch?v=VOPeKDgYhIU