How to drive a RAILSIM (German version) train?

Well, the overall handling of the program and the basic train driving functions are nearly the same in both versions of the RAILSIM program (RAILSIM USA/CDN 1.26 and RAILSIM 2.90 - or the demo versions).

The most significant difference between them is that running the German version requires knowledge of the safety systems used by the German Railroads.

First of all there is the "SIFA" = "Sicherheitsfahrschaltung" or say "dead-man-button".
It's a foot pedal to be pressed permanently but it has to be released and pressed again at least every 30 seconds.

RAILSIM simulates the SIFA using key [0] or [ ] (space-bar).
Do not press these keys al the time (you'll get an overflow) but press the "SIFA-key" at least every 30 seconds.

Then there is the "INDUSI" = "Induktive Zugsicherung" similar to Automatic Train Control (ATC) in America.
Any restrictive signal or speed sign announcing speed restrictions lower than 100 km/h require acknowledgement by the driver/engineer.

When you passed such a signal you will have to press the "INDUSI-Wachsamkeitstaste" (Acknowledgement-Button) [ENTER] within 3 seconds.
Do not press the key until you really passed the signal (or sign).

After passing "Halt erwarten" (signal indication "approach") or "Langsamfahrt erwarten" ("approach low speed") your speed will be checked after a certain time.
A yellow figure will appear over the traction/braking indicator and disappear when your speed was checked.
Time and speed vary with different train types:
Passenger trains (except with slow locomotives) have to reduce their speed to less than 95 km/h within 20 seconds.
Fast freights (and passenger trains with slow locomotives) have to reduce their speed to less than
75 km/h within 26 seconds.
Slow freights have to reduce their speed to less than 60 km/h within 34 seconds.

If the actual allowed speed is more restrictive you must not violate this limit too (of course!).

When you approach a stop signal make sure you do not violate 65 km/h / 50 km/h / 40 km/h (according to train type) when you are closer than 250 meters to that stop signal.

When you approach a new track speed limit make sure you are less than 15 km/h faster than the new limit
250 meters in advance of the start of the new limit. At the start of the limit do not violate it by more than 10%.

Any violation of these rules will result in a penalty brake application ("STOP").