Take a look at this great thread:

The great tallscreen screenshot project thread!

As it says in the first post it was started just for fun, and I browsed the thread for a chuckle, but then fell in love with the portrait rendition of Hitman: Blood Money. I think the orientation really suits the scene, frames the character better than the normal landscape view, and I'd like to play the game that way. And I immediately wondered if it could be done in stereo 3D too.

Can it be done? How would you achieve it? I did find this thread, but didn't want to post in there as it's rather old now. I'm guessing any kind of shutter glasses/monitor combo is out and I don't really know much about the other display types. I know there are a lot of DIYers on these forums and would love to know all the ways this can be done, then anyone who's interested in playing something like this can pick the way that suits them. What do you think?

I've done this with the Zalman and I guess it works, but due to the narrow viewing angles it is pretty much unusable. And most games do not work in weird resolutions like that. Could be cool for some stuff.

You think it could be done with a planar mirror setup?

Physically, sure. I just don't know how well the software would work.