The only problem with the game I have, and the one that annoys me A LOT is this:

Whenever I move the mouse, look around in the game, my entire screen and all the textures on it change in a slight but very noticeable way. They simply change in the level of lighting from normal to darker, or from normal to a bit lighter. This means that my entire screen constantly flickers in the level of brightness on all the objects in the world.

This happens indoors and outdoors. When inside buildings I can simply look at the floor or the walls and if I move my mouse just a bit my whole screen goes from lets say brightness 50/100 to 52/100. Then when I stop moving the mouse it goes from 52/100 back to 50/100. But if I just keep moving my mouse in a circle then it's always 52/100. That is until I stop moving it when it goes back to 50/100.

(52/100 and 50/100 are just made up numbers so you understand the change that I see)

I made a video where if you keep looking at a fence you will notice it constantly changes in brightness when ever I move my mouse a little. But if I keep it moving in a circle you can't notice anything.

http://www.youtube.com/watch?v=0VVVf09IwEw