Like the Unity documentation website, Google also maintains an in-depth guide for the Google VR SDK for Unity set of tools and examples. This SDK provides the following features on the device:

• User head tracking
• Side-by-side stereo rendering
• Detection of user interactions (via trigger or controller)
• Automatic stereo configuration for a specific VR viewer
• Distortion correction
• Automatic gyro drift correction

These features are all contained in one easy-to-use package that will be imported into our Unity scene. Download the SDK from the following link, before moving on to the next step: http://developers.google.com/cardboard/unity/download.

At the time of writing, the current version of the Google VR SDK for Unity is version 1.110.1 and it is available via a GitHub repository. The previous link should take you to the latest version of the SDK. However, when starting a new project, be sure to compare the SDK version requirements with your installed version of Unity.