Well, it doesn't only have to be "only in VR" mechanics, it also has to be a really really fun game compared to almost all the other games you could at the moment purchase and play on your normal PC with a normal monitor and no extra $1000 investment in hardware..

I've tested VR sporadically ever since the first Oculus Rift came out, and I just get a headache after 15 minutes and that kind of has ruined it for me forever I guess as I now associate VR with motion sickness, bad ergonomics etc. That's very personal of course, I know there are others who can run around in VR fine for a whole day without these reactions.

Anyway... the game has to be outrageously good for me at least to use a VR version instead of just sitting on my chair staring on the screen with a cup of tea next to me.