Procedural content generation is good to generate a lot of content but what I haven't found out yet, is how to use it to let the world change over time. I could easily create different "galaxies", but each time it will be only a snapshot.
I think after the initial generation step, there needs to be a simulation, which can calculate changes over time. I'm not quite sure how to store such changes in the saved games, but at least theoretically it seems a feasible approach.
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