Simulator ExpressDoggettData marketed this tool that I put together. I was based on code written for the MCI Router CBT. It was a relatively complex bit of Toolbook code that would encode simulation settings into a book. The Simulator Express engine was stored in a system book that could be updated with newer versions.
A simulation has a series of states, triggers, and actions. The programmer simply has to explain how the object to be simulated behaves. The engine takes care of the rest. The real benefits come when the object gets complex like a router or a car. There would be literally thousands of lines of complex code to reproduce what Simulator Express does easily.
Simulator Express shipped with a standard set of objects that could be used in a simulation. There were standard light switches, blinky lights, and cables to plug and unplug. The most powerful was the console simulator. It could easily model an operating system like DOS, and would interact with the entire rest of the simulation. For example, this could model an exhaust gas computer hooked up to a car. As you tune the engine the analyzer would give different results.