Are you sure your sickness isn't being caused by an unnaturally small or high Field of View (FOV)? This is a common cause of motion sickness-like symptoms in gamers. Usually adjusting to a FOV of 90-100 degrees fixes this (depending on your screen's aspect ratio).

Then it is a good thing that we don't know each other in real life.

People would get motion sickness watching me playing Descent.

I would turn around when moving forward just for the sake of it.