My suggestion is that decay of large structures be made visually interesting. As houses, towers, walls and pillars decay, their model should be switched to ruined versions of themselves, meaning
* fallen roof and rubble,
* ruined walls and overgrown moss,
* and finally only the basic ground frame of the structure.
If left ruined for too long, the area could also be assigned an increased spawn rate of certain animals and herbs.
I think this would give an interesting feel to late worlds. Exploration of ruins is a common place in RPGs, and discovering the past history of a world is a kind of self-sustaining content for those inclined to that. Plus, it would look good on pictures.
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