The addition of a head mounted display would probably have a similar effect to increasing the graphical capabilities of a game console: increasing the visual appeal of a game. This would be particularly true if the headset was more immersive than a standard television or possessed solid 3-D capabilities, as I discussed in my last post. However, it is important to remember that this increase in visual appeal is limited in what it can do. For example, merely improving the graphics of a game can improve the reception it gets, but it won't solve any problems inherent in the game design. Fancy graphics or 3-D capabilities in a sense are novelties. They might draw in people, but they won't be enough on their own to sell a game, console, or peripheral device. In particular, decades of bad 3-D movies, the limited commercial success of IMAX, and the currently slow adoption of HD television demonstrate that technology that relies solely on an improved visual appeal is not necessarily capable of being marketable.
In summation, a high-quality, possibly 3-D, head mounted display will draw interest and attention, but will quickly be discarded as a useless gimmick if its creators and game designers rely on selling it entirely based on the improved visual appeal of compatible games. Thankfully for the head-mounted display, it does possess an unique advantage that can change game design in a somewhat significant way: what is displayed by the headset can only be seen by the person wearing it.
Having information that is limited to only one player can be a very useful game design tool when dealing with multiplayer situations. Back in late November, I discussed the problems that existed with local multiplayer (both co-op and vs.) on current console systems. Right now, on-line multiplayer is generally a superior experience to local multiplayer, because players don't have to deal with a split-screen when playing people over the internet. They get to have the entire screen to themselves. However, if multiple players each had head-mounted displays, that problem would go away. Everyone would be able to experience the full game experience. Furthermore, it would open up some interesting multiplayer design space, where one player could be using a headset, and another payer could be controlling the game in a different way on a TV screen.
I admit that this advantage is a relatively small one. Of course, head mounted displays can have a lot more interesting uses for video-games if they go beyond just a graphical display device and allow for unconventional control schemes. However, I will abstain from speculating about that impact of such a device until I get a chance to try one out. For now though, the utility of a HMD is mostly limited to an increase in visual appeal and an improvement in local multiplayer game design.