VR would be best suited to games where you remain seated, mostly look forward, mostly travel in a straight line and the game controls map onto equivalent virtual controls. Something like a race car, plane or space ship.
I suppose a FPS would be possible providing the person can remain seated but there are obvious control issues to figure out. For example if I look around for real, e.g. turn my head to look over my shoulder, what does that mean in a game where I'm lying prone staring down an iron sight at the time? Or if I'm standing in the game and I I look right in real life and then click aim - does my virtual counterpart assume some ludicrous pose to accommodate my action, or does it reorient itself facing forward while my real self is still looking over to the right? How does it reset the camera afterwards? It could prove messy and just serve to increase the chance of disorientation.
On the plus side, I guess VR could pull of a very realistic FPS Saving Private Ryan game where the people puke their guts up on the virtual landing craft and stand a good chance of serious injury when they storm the beaches.