I can see it, but it takes quite a bit of time, and is quite tricky to maintain- especially if i tilt my head slightly. Not the kind of thing you want to happen when you're in the middle of a game.
I have done these before, and remember the first time was much harder, so i guess it could get easy with practice. However, too much of this might make one go cross-eyed on a permanent basis.
Because of this, parallel viewing is arguably better, however, you are then limited to using very small screens- about the size of the distance between someone's eyes, unless you want to set up some kind of double periscope thing in front of your monitor.
Anaglyph 3d might be better. It has been done in DBP. (just search for it) I know I asked people about it a while ago, and they were quite helpful. Apparently it's not that hard to do. I have yet to get around to making it though. Anaglyph doesn't stop you from using colour, although you need to be a bit careful about what colours you use- e.g. you couldn't have a level where everything was shades of red, because one eye would just see black etc. Just wear your red/cyan specs whilst designing your game and check that object outlines and textures can be seen through both lenses.
