Roberto Dillon 
2D to VR with Unity5 and Google Cardboard [PDF ebook] 

The book provides an up-to-date introduction to the latest version of Unity and its workflow by guiding readers through various prototypes. These range from 2D to 3D game concepts for PC and mobile, will allow readers to get acquainted with several important concepts and allow them to become competent Unity developers able to learn at their own pace. The book starts by introducing Unity and proceeds in building a basic understanding of its main components by developing a first, simple 2D game before proceeding in developing a full casual game to development of a simple but immersive 3D game concept to be tested first on PC before exploring how to port it for mobile VR.using Google Cardboard.