Updating to Oculus Runtime 1.3

To develop for Oculus 1.3 you'll NEED to specifically be using Unity 5.3.4p1:
https://unity3d.com/unity/qa/patch-releases

(If you are using the 32-bit version of Unity, you will need to use the 64-bit installer to install just the build engine for PC/Mac/Linux)

You will also NEED to download the OVRPlugin separately and patch Unity:
https://developer.oculus.com/downloads/game-engines/1.3.0/OVRPlugin_for_Unity_5/

The OVRPlugin just mentioned has very special and particular instructions:

After you have downloaded and installed Unity 5.3.4p1, take these steps to install OVRPlugin:

1. Close the Unity Editor if it is currently running.
2. Navigate to the following directory: C:\Program Files\Unity\Editor\Data\VR\oculus.
3. Delete all contents of the directory.
4. Extract the OVRPlugin zip and copy all files into the directory C:\Program Files\Unity\Editor\Data\VR\oculus.

Note: Do not install OVRPlugin version 1.3.0 with any version of Unity other than 5.3.4p1, or it will not work properly.

Finally, you'll have to update the Oculus Unity Utilities:
https://developer.oculus.com/downloads/game-engines/1.3.0/Oculus_Utilities_for_Unity_5/