Playing offline, you often build a network, or a network section, and then let the game run. Thankfully you need few micromanagement to play Simutrans, so you can fast forward till you have more money or more pax and need to/can build something else. But sometimes snags happen (e.g. vehicle stuck, station overcrowded and so on).
It could be nice to be able to add triggers to game speed on selected events, basically back to normal speed and pause.
Events which could trigger these changes are, e.g. vehicle stuck, station overcrowded, reaching a given account balance, margin turning into red.
An example of settings could be:
vehicle stuck -> pause game
station overcrowded -> normal speed
margin turning into red -> pause game
account balance reaching 500,000.00 $ -> normal speed
The player could let the game run alone, possibly in fast forward, knowing that no bad event (network completely stuck, bankruptcy) can happen and he can avoid missing opportunities having the game back to normal speed.
I think the scriptable scenario effort of Dwachs would easily allow this.