This is Sebastian Lague's excellent game from his "Unity Create A Game Series", turned into a VR first-person shooter with the help of GoogleVR and MFi controller support for iOS.

The original tutorial series is on YouTube, starting here: https://www.youtube.com/watch?v=jdv8erC7ML8

Here's a video of the VR version in action on an iPhone 7: https://youtu.be/NKi4ICVdnZw