Hopefully this will mostly Just Work™ and you won’t have to think about it.
All the data in the Quest Objects is saved automatically, along with the basic variables you add to your scripts.
However, references to game objects and more complicated things you add in your scripts aren’t saved automatically.
- If you have to do this, you can restore references in your scripts after a game is loaded in your rooms OnPostRestore functions.
If you patch your released game, older save games will usually still work (within reason). But when making changes to a released game you should add new variables to your scripts below the old ones. And make sure you test things so you don't break people's saves ;)