[m_darkTemplar]

I've had a lot of time with the development version of the Oculus Rift, and there's more things than just that which will cause headaches/motion sickness. Many things where the eyes and other sensors disagree will cause headaches.

In game side to side motion, rapid changes in heights, UI that is not fixed in world space, things that are too bright, taking camera control away from the player (slow horizontal rotation seems to be okay, vertical rotations cause immediate headaches in my testing), FPS lower than 60, etc. The FPS one is particularly interesting I was mirroring on a monitor, and I couldn't tell that the FPS was low(it was running at around 35fps), but in the Rift is was super obvious something was wrong.

I attended a talk for developers given by the founder recently, and he mentioned that stairs also are troublesome, and ramps work better right now. Something to do with how the brain has been trained to know the sensation of climbing stairs.