Okay fair enough, yes you did explain that well enough :) I never played Legend of Grimrock, but ive seen screen shots of it and the passageways did look very narrow which lends itself to those kinds of movements, i think this was also how very early (mid 90s) first person shooters did their movements also such as Castle Wolfenstein? thats a long time ago i played that hehe.
I will try disabling 'limit mouse look'. I also tried out use mouse movement which i think i will use. I hope you do revisit it in the future as per suggestions from lectronice.