"Room scale VR" is this gimmick mainly promoted by HTC/Valve, where you play the game by standing up and walking around your room, using two controllers that are tracked by the computer. As your head movements are also accurately tracked, the computer pretty much creates a virtual environment and it looks exactly like you were within that environment. It can look astonishingly real and impressive.
It certainly does make for very impressive tech demos. But does it have a future in actual gaming? As an actual game mechanic? I have my doubts.
Consider one of the most basic core things that's common to almost all video games in existence, with only few exceptions: Movement. You play the game by moving the playable character. In games depicted from the first-person perspective, the "playable character" is essentially the "camera", and you play by moving it from place to place.
And "from place to place" usually means significant distances. From room to room, along corridors, inside a big complex, on the streets of a city, or even a wide open outworld that may be tens of miles to every direction.
This is absolutely ubiquitous to almost every single game genre, and almost every single individual game, with very few exceptions. (I don't think we need to count games where the idea is not to control a playable character, such as board or card games, or pinball.)
It is quite ubiquitous to almost all games because severely limiting movement would be quite boring. There's only so much that you can do while restricted to a very small confined space. It wouldn't make for much of a game. Essentially you would be restricted to whatever game can be played within such a confined space. Maybe the only two even moderately enjoyable examples that I can think of are golf and table tennis. (Of course in real life golf requires a lot of walking, but in video game format that's usually completely skipped, and instead you are just teleported to the next location, and that's completely fine.)
HTC/Valve is envisioning a future where "room-scale VR" is the quintessential game mechanic. And all they have to show for it are some technical demos that are "played" through quite quickly. They may be impressive to experience, but they don't make for much of a game, really. There's only so much that you can do in these demos before you get bored due to repetition, lack of variety, and lack of things to do.
Note that I'm contrasting this with the sit-down experience that's also possible with VR headsets. There is significantly more game mechanics possible in this scenario, and that's where I believe the future of VR is, if it has any. But seemingly this is not something that HTC/Valve is promoting at all. They only want "room-scale VR".
The problem with a standing-up experience is that the computer cannot move the camera on its own, because else it may well cause the person to get confused and lose balance. The computer must constraint the camera accurately to the movements of the headset. Moving the camera otherwise would even be potentially dangerous, if people get confused, lose balance, fall over and hurt themselves. So it just can't be done in standing-up mode, if for nothing else, then for safety reasons.
Thus this severely limits what kind of game mechanics you can use. Sure, the game can "teleport" the player from place to place, and this does not cause loss of balance or confusion. But a video game loses quite a lot if you just teleport a few feet at a time, rather than actually moving. Much of what makes a video game a video game is lost. It more becomes like a shooting gallery, where the environment changes from time to time. This is essentially a trick to circumvent a limitation in how the device can be used. I don't believe that teleporting from place to place is even nearly as enjoyable as actually moving from place to place.
And that's not even talking about the fact that it's rather unfeasible to play a game for hours while standing up. Imagine if you had to play all your video games standing up.
I can't help but to compare this, once again, to the infamous Kinect. The similarities in terms of game mechanics are very noticeable. Both work primarily while standing up, both are controlled with your body movements, and both are very limited in terms of game mechanics. And in most cases, the game is just a static shooting gallery and little else. (In fact, the Kinect could be even more versatile than VR in the sense that it could perfectly well move the camera freely without problems, something that cannot be done in VR while the player is standing up, for safety reasons.)
And we all know how successful the Kinect was. That's to say, not very.
I can't help but to consider "room-scale VR" to be simply a glorified Kinect. With exactly as much prospects for the future and triple-A games.