Google Cardboard, a simple viewer for virtual reality content, has gained traction in what could be one of the more interesting experiments in so-called immersive experiences.
While Microsoft's HoloLens and Facebook's Oculus garner a lot of attention and headlines, Google went simple with virtual reality. After 19 months, Google said more than 5 million Cardboard viewers have shipped.
In a blog post, Google also said that there have been more than 25 million installs of Cardboard apps on Google Play. And YouTube has delivered more than 350,000 hours of virtual reality videos.
Most of the traction in apps and content for Cardboard came in October 2015 when Google created a more-friendly SDK for developers and accelerated through the end of the year. The Cardboard approach for Google is to rely on Android developers, its installed base and inexpensive players. Other virtual reality efforts require more effort and money.
Overall, the ramp for virtual reality will be slow, but all the technology giants have some kind of bet on the technology. Google's Cardboard effort is the centerpiece of a broader effort to bring virtual reality mass market--and ultimately play in VR ads.