Zusi (short for the German word for "train simulation") is a railway simulation focused on virtual driving of trains. Unlike most other simulations the aim is to simulate the real driving experience in consideration of driving physics, signalling, and technical safety installations (mostly German types) rather than heavily rendered environment.

Included editors allow to create complex scenarios with more than 100 trains and engines, time schedules, track design, and buildings. Also provided are hundreds of kilometres of railway tracks as well as loads of (mostly German, Swiss and Austrian) engines and rolling stock. User created content is available via add-ons.

Zusi 3

Version 3 is a complete rewrite of the program and features vastly improved graphics as well as an even more accurate simulation of driving physics. It comes in a version for professional users (like railway companies) and a slightly less functional version for home users; the latter is only available as a demo version at the moment.