There should be a warning that pops up ingame whenever you exit a simulation that is not saved yet (exiting such as going to the save browser or using the ingame keycombo to exit).
It would say: "Save simulation? Do you want to save this simulation before you leave? Yes (Takes to save making screen) No (Exit).
There could be an option in the simulation options to turn this on or off.
Which is the problem - unpaused saves, those which you simply played for a little bit, etc would always prompt. Another idea would be an autosave feature. Like in a temporary directory or something to allow recovery.
The best way to do auto-save would be to make a timed autosave system which saves save in specifoc period of time which is configurable like every 5 or 10 min and then auto open the last saved save when starting tpt.
He was suggesting that there should be a warning before leaving TPT, if you read it entirely that is. You would also know the warning was about saving before leaving. Sorry for the necro.