Google last week announced an updated app for its minimalist Cardboard virtual-reality viewer, as well as software development kits for both Android and the Unity game engine. It also published new building specifications for those interested in making their own Cardboard viewers and announced that it’s hiring more people to work on the project, with five new positions now open. More than half a million phone-based Cardboard viewers have been shipped, Google said. Cardboard apps, including games and concerts, are now available on Google Play.
I really don't think that was joke of google. That was google clearly saying it really wanted to enter the VR industry. Thanks to this, lots of apps developer started to make VR games and lots of companies started to sell google cardboard and VR headsets:
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Google’s Cardboard VR Kit Is Really No Joke
Posted by: Katherine Noyes December 17, 2014 06:55 AMGoogle last week announced an updated app for its minimalist Cardboard virtual-reality viewer, as well as software development kits for both Android and the Unity game engine. It also published new building specifications for those interested in making their own Cardboard viewers and announced that it’s hiring more people to work on the project, with five new positions now open. More than half a million phone-based Cardboard viewers have been shipped, Google said. Cardboard apps, including games and concerts, are now available on Google Play.
http://www.virtualcardboard.com/en
http://www.durovis.com/
http://www.imcardboard.com/
also you can find some higher quality VR headsets like oculus rift but there are more expensive