Fable | The "Living Population"

Having lively NPCs were 'non-negotiable' when the team started, over 1000 of them

Fully voiced conversations with any NPC

NPCs are 'persistent' with daily routines- you can follow anyone around all day and watch their autonomous actions

Each NPC has their own personality traits, likes and dislikes

You can go into any building or house

Every house can be purchased and you can live in it

You can romance, marry and have kids with almost any NPC

Players can marry more than one, and NPCs will have opinions about that too

You can also hire and fire each one of them

Your reputation is affected by what you do out in the world and each character will have their own opinion of you

Your reputation can be different from place to place depending on your actions, so you can have one identity in one town and a whole different identity in another

Reactions vary, some NPCs will praise you, scold you, mention things you did, catcall you, and shop prices can be affected

You can do things to rebalance your reputation, or pay the "Town Crier" to start shouting about a new reputation to overwrite your old one

Each NPC has their own bed in the game, each town has to be functional