Off the topic title alone, I’d say Animal Crossing fits the bill. I mean, it’s Sims but you build up your island. You technically colonise the archipelago in the DLC, and you can put castle walls and turrets around your house.

There are a bunch of games like that. Animal Crossing is just the one I play. It’s made for kids, but it’s secretly (?) post-apocalyptic (I was shocked to find out but apparently it’s kinda common knowledge in the fandom?), but there are others like that.