Valve is a critical player in the modern resurgence of VR. They are known for their friendly competitions and cooperation they had with Oculus in the early days of virtual reality spanning from July 2012 to March 20113. Blake Harris' History of the Future does a great job of laying down a initial timeline (albeit without complete citations as well as an unknown amount of dramatization), but in my interview with Harris he also shared with me beyond very limited conversations with Valve's Joe Ludwig and Alan Yates, he didn't have any conversations with any current Valve employees. The only Valve representatives he was able to talk with were former Valve folks who left to work at Oculus. Harris had access to some e-mail correspondence between Oculus and Valve, but in the absence of Valve's participation, the overall perspective captured in Harris' book is heavily influenced by Facebook's side of the story.