Gritty is difficult to reproduce in a simulator or any computer program for that matter. The real world isn't made up of splines and textured grids, it is truly random. From the hand-laid wooden ties to the ballast edges that have roughed it out in time and weather to the roads that have been battered by millions of tires and bleached by a thousand summers, these are all details that can only be reproduced by a truly procedural and random algorithm, one that I have yet to see in any software, even Crysis and Far Cry, both of which considered to be the pinnacle and cutting edge of 3D gaming graphics.
Until then, the most we can realistically expect and probably get are repetitive textures and splines sugarcoated in pretty light and shadows.
Edit:
To answer your question Paul, Spin Tires was created with one purpose; to simulate mudding and off-roading in the jungle. How will it hold up to the myriad of environments that Trainzers regularly reproduce? Industrial wasteland, urban sprawl, panoramic 10km-draw-distance-worthy mountain passes? You like the mud aspect, I'm sure and so do I, but there is little of that (other than the texturing) that can practically be applied to Trainz. For one, we don't usually take our trains rolling in the mud.
