In this guide, we’ll start by defining Google Cardboard and see how it fits in the spectrum of consumer virtual reality devices. We’ll then contrast Cardboard with higher end VRs, such as Oculus Rift, HTC Vive, and PlayStation VR, making the case for low-end VR as a separate medium in its own right. We will talk a bit about developing for Cardboard, and consider why and why not to use the Unity 3D game engine versus writing a native Android app in Java with the Cardboard SDK.