Try wearing sunglasses.
What ways are there to permanently cure myself of motion sickness caused by first-person video games?
I have heard adjusting the frame rate can help.
btw - playing lots of FPS games may cause you to lose grey matter, according to this article:
au.news.yahoo.com/world/a/36646265/shooter-video-games-damag
Adjust the field of view. Sometimes it's too narrow and forces you to over focus.