Zusi 2 is a german railway simulator which depicts driving a train in a simulated timetable on a complex network. In comparison to other railway simulators, Zusi focuses on realism in regard to train physics (traction and brake systems), train protection systems (german systems SiFa, PZB and LZB in particular) and operation.
Over time, a large number of vehicles and routes has been created by the community. Most of these are german routes, but routes in Austria and Switzerland have been created as well.
There has been a large number of re-releases, incorporating new routes and vehicles, but for customers with older versions the additional content is available for free on the web.
A number of external programs extends the functionality of Zusi 2, for example ZusiSoundthesizer, providing a more flexible sound model especially for 3AC engines, and ZusiDisplay, a simulation of electronic timetable displays (EBuLa), passenger information systems and a variety of other displays used in a train cockpit.