OK, When this whole VR headset started to culminate into FPS games I knew this would be the problem - how to move, aim, and shoot. I knew developers would find it difficult to achieve what people expect.
Here's what people expect for the words 'Virtual Reality' FPS to be lived up to:
1) Aim only the character's perspective with your head (camera)
2) Aim your gun seperately with your hands.
3) Movement is "not on-rails".
In traditionally controlled FPS games your cross-hair is locked to the center of the camera. If you given a headset and played a game like that, you will get very tired of having to aim the gun with your head. And it isn't realistic.
So the challenge for developers is to create a new input method that lets you move, and aim your gun, and camera-look with your head at the same time, while seeming like "virtual reality".
That, my friends will be a long time coming. A VR headset without the rest, will be disappointing. That's why we're now hearing about VR interactive movies and on-rail turret games etc. This is when they hype dies off. VR isn't ready yet.