There are at least two examples of train simulator software commercially available for Windows PCs. The development focus over the last 15+ years has been on ever-improving 3D graphics appealing to the general public. I find the games good-looking and entertaining. I don't believe that either one has truly accurate physics that would help someone learn the nuances of handling a heavy train in mountainous terrain.
It's possible that in the future, V-scale (as virtual railroading is sometimes called) will compete with or even exceed the physical scales in popularity. These simulators are immersive, more realistic than small-scale models in terms of train-handling, and require NO physical space! And at least one of the consumer simulators has an online "multi-player" feature where you can run side-by-side with other human-controlled trains. Very cool!
