A railroad simulation I think of should have all the best ideas from different existing simulations but without all the problems.
- 3D editor
- scalable models, tracks, bridges, tunnels, etc
- simulation is running during editing which whould allow growing of the railroad as needed and testing of the rest in the same time
- sitting in a trains and drive it
- automatic routes, junction control, signal control depending on train settings destination
- open file format of models, rolling stocks, etc
- open and simple file format of the szenario which would allow external tools to modify it
- easy add more space to a szenario if it grows
- simple scripting language to allow complex automatic routes that can't be handled by the buildin code
- open interface for extensions (plugins)
- trains simply drive until specifiy tracks or triggers on a track control them (maybe by script)

