[setr]

I think that’s just more a result of the game style/architecture. I don’t think there’s much hidden state that’s not encoded into the map/entities, and even things like AI is I think ultimately preserved as a simple stack of pending tasks.

So being a proper simulation, and combined with the lack of replay, you can almost entirely discard the past events. The game is largely modeled as f(world-state, sim-rules) -> world-state, and so you simply take the old save and continue running it under the new simulation rules, and no one has to really care how many rule sets the world has seen. It only matters that they produced a valid world-state, every time.

[meheleventyone]

The issue with saves and compatibility is that the saved world state needs to remain a valid world state in a new version. This can be as simple as initialising missing data to sensible defaults or a lot more complex if simulation changes have caused the world state to change significantly. Then to avoid breaking things you need to somehow migrate the old data to the new data. And you may need to do that several times if someone loads a save from eight versions ago.