BVE is an in-cab only view railsim designed for free by a Japanese programmer. It is very realistic though, containing rail can't, gradients, variance for roughness of junctions etc and suspension movement.
Despite all the advances made in Railworks, Trainz et al, I still find it the most realistic and satisfying to drive.
All of the routes and trains are free too, whereas Railworks requires similar money to a model railway.