I have a Oculus Rift CV1. You dont have to have Oculus Home running, it will start automatically. I dont have GTA5, but can confirm that Diablo 3 works fine.
@Solarise: Do you happen to have any more info on this? I was really hoping to get VorpX working with Overwatch. If there is any source for this, I would like to make a support case with Blizzard and try to see what can be done about it.