The fact that Google Cardboard is open mobile VR and it comes in all shapes, sizes and prices is precisely why we love it. But Google has recognised that with so many viewers, it needs to do a spot of quality control.
That's why it has launched 'Works with Cardboard', a certification program for third party Cardboard viewers so that we know each particular viewer "works great with Cardboard apps and games". Manufacturers can apply for the certification from Google itself.
But there's more - anyone building a VR viewer can send details of its focal length, distance between the lenses and input type to Google which will then have the parameters it needs to optimise content for that viewer.
All VR fans have to do is scan a QR code on the side of the device to make sure all Cardboard videos and games are now optimised for that viewer's set-up.
It's a great move as there's so many different Cardboard viewers to choose from now - as well as making your own - and the optimisation in particular will greatly improve the Cardboard experience.
In the blog post announcing the program, Google also revealed its acquisition of Thrive Audio, based out of Trinity College Dublin's School of Engineering, to work on immersive, spatial audio for VR. It also boasted that there are now hundreds of Cardboard apps to try out.