How about being able to make towns with NPC residents?

[Clankdoom]

How awesome would it be to be able to create your own thriving towns filled with NPCs that you can talk and trade with? Maybe sentient creatures, or lost human survivors looking for a place to stay. Think of it as the house building system in Terraria: you'd need to create a house with liveable conditions for the NPCs to move in. Not only that, but you might need to have special decorations for certain NPCs, such as a potion or cauldron for an alchemist. You could also, of course, name your town to anything you want (please be appropriate.) It would definitely give the game that extra RPG feel to be the founder of a flourishing town.

 

[Antnest8]

This would be cool, if only we knew more about how NPC's work so we can understand how much work is needed to do this