You were looking for ways to set your game apart? What about implementing a hitbox on the player and having the nature of the hit impact not only health but ability?
Get shot in the head? Dead! Or maybe you get lucky and only lose an eye. With VR you can do that and suddenly the person can only see on one side and stereoscopic vision is thus also gone.
Get shot in your gun arm? Congratulations, you now move slower and have to shoot with your other hand!
Get shot in your non-dominant arm? You move slower and reloading takes a lot longer. Two handed melee weapons would be out too.
Get shot in the leg? You now move slower and can't jump as far.
Get shot in the abdomen? You now move slower and have a limited time to finish the level or you bleed out.