3D is a feature best appreciated by an audience watching a game being played -- because the player isn't likely to notice the effect at all.
There was a lot of 3D stuff on display at PAX East this past weekend. Many 3D demos were present from publishers, developers, or video card manufacturers for fighting games, shooting games, or racing games. In particular, Mortal Kombat and Crysis 2 had a very big 3D presence. Displays featured a demo of each game being played on a massive 3DTV with buckets of glasses available for curious attendees. After watching both games being played in 3D for a good long while (sadly I didn't get a chance to play anything on the 3DS), I came to realize that 3D is a feature best appreciated by an audience watching a game being played, but the player isn't likely to notice the effect at all.
To be perfectly clear, I'm a proponent of 3D stuff in whatever form it takes. I like the effect, it doesn't hurt my eyes, and I don't mind the glasses. But like any new piece of technology, there's a learning curve that we have to endure as artists learn to use it.
Crysis 2 looked great in 3D but only when the effect was noticeable, which wasn't often. One of the most cited drawbacks of 3D is that our eyes need extra time to process the image, so fast cuts in a movie are detrimental to the effect since they don't allow us to actually process the depth of an image. The same goes for any kind of 3D effect in games. If the camera pans around too fast, then our eyes don't have time to process the depth of the world, and the 3D effect is made negligible. In any FPS game, players spin and turn and zoom down the iron sights so fast that our eyes never have time to truly see the 3D. And this will never change. An FPS player must be focused on the world and the enemies within it. He has to be aware of his surroundings to survive and that means always being on the move. An audience isn't required to be as attentive to the world, so they're free to admire more static images, like the gun or UI elements that always stay in place on the screen. Since these objects don't move, our eyes have plenty of time to process the image and we come to really appreciate the incredible visuals of Crysis 2 -- at least as they’re applied to the guns. It's too bad then that the player is never looking at the gun but at the crosshairs in front of it.
Any game in which the player controls the camera is probably not a good fit for 3D. Players have a tendency to swing the camera around too much and are therefore constantly destroying their own 3D experience. This effect might be less pronounced in a third-person action game since our avatar would have a static position on the screen and players must pay attention to this particular static image, unlike a gun. However, the “camera swing” problem would still exist whenever our eyes move to the horizon. I believe that any game with a fixed camera position will always be better suited for 3D. Racing games, fighting games, point-and-click adventure games, most sports games, or action games like God of War and Resident Evil (the old ones). These could all work in theory, but they may still suffer from the “player focus” problem. I’d have to play one to find out.
Unfortunately I don't own a 3DTV, so I can't experiment with every (or any) 3D game that comes out. But after seeing Crysis 2 in action, I'm confident in saying that 3D should not be used for FPS games, ever. Despite the wonderful visuals in Crysis 2, good graphics don't necessarily translate to good looking 3D. Even its use in fighting games is debatable. If the game is going to be played in lots of tournaments then it might be worthwhile to invest in 3D since you know there will be a big audience of spectators.
As one of the few people that seem to like 3D, I’m excited to see the technology and its usage mature. I’ll probably get a 3DTV eventually, but that day is a long way off. Until then, there’s always PAX.