Just when you thought virtual reality was a two horse race. Oculus Rift and its $2 billion jockey look to be cruising down the final furlong with Sony’s Morpheus hot on its heels, when all of a sudden, out of the pack comes Google’s Cardboard. Is this a donkey that’s got in with the thoroughbreds or a genuine contender?

Cardboard - unveiled today at Google I/O - is an eponymous DIY headset equipped with cheap lenses into which you insert your smartphone. Simply assemble the headset, download the Cardboard app and you’re ready to enter a budget virtual reality - all for a very affordable $20. The app comes complete with head tracking through the phone’s accelerometers and gyroscopes, and includes several VR demos. Users can look around a virtual Hall of Mirrors, fly through Chicago using your head to steer, view YouTube videos as if you’re sitting in a cinema and explore 360-degree panoramic photos.

With Cardboard, Google hope to encourage developers to build the next generation of immersive digital experiences and make them available to everyone. While this may not be the innovation that brings expansive, immersive worlds to virtual reality gaming, it is a surprise offering, jumping the queue while all we currently have is speculation.

In a similar vein, we recently covered Altergaze, this time a 3D printed set of goggles that uses your smartphone power to deliver a cost-effective, virtual reality experience.