BVE Trainsim is a FREE Direct 3D Japanese Cab View train driving simulator, made in Japan by Mackoy. It offers a realistic cab view, excellent sound, and very good train physics. Although originally limited to Japanese routes and trains, there is now extensive English language support, and routes and trains available from just about every continent in the world.
The program includes detailed per-car simulation of the brake systems, friction, air resistance, toppling and more. In 3D cabs, the driving experience is augmented with forces that shake your simulated body upon acceleration and braking, as well as in curves.