Not necessarily sick - but the biggest thing missing from desktop simulators is the feeling of the g-force. It is very easy to pull crazy G-forces because all it takes is a simple push or pull on the joystick.
Maybe the awareness of G-force is something that *might* be possible to enhance throuhg "secondary" senses - like the effects on hearing, or vision, which can be simulated on the computer, while actual physical motion is much harder.
Jet fighters also have the "G-pants" which basically inflate with air when you pull high positive G's - to keep your blood out of your feet and in your head, so you don't faint so easily. This could be something you *could* do for a simulator, but it would also require special hardware. But I think the brain might be able to adapt to the understanding that pressure on your legs means higher positive G.
Vision and hearing, *might* also be used to enhance the feeling of g-force so you sense how the aircraft is moving, even though you don't sense it as motion. And that wouldnt require special hardware. It would indeed be interesting to try how adding a "hum" or whine sound that increases as you pull G's would complement the red/blackout effect.
Also, would those things work, if they were "supersensitive" even to low g-forces? A bit like the the head tracker devices that enable you to look all around the scene by moving your head a lot less to the sides (because you still need to see the screen!) - those are over-sensitive, but the brain adapts to the setup very quickly.
Maybe our brain could do something similar with exxagerated g-force cues through hearing and vision? Might there be some other ways to do this? Maybe a low bass rumble that could be felt though a subwoofer? This stuff might be interesting to play with and maybe it could work out!
//T