At the beginning of a game you have the choice of spawning in a certain number of NPC Players.
These players would start near the same spawn point.
They would go out mine and build their own houses and do stuff a normal player would do.
So, they'd mine for a certain amount of any resource to make a "blueprint".
These "blueprints" could be anything from a house to a farm.
(Different forms of mining, strip mining, etc.)
They'd wander out and come back to their house.
You can trade with them for items they have and become an ally and with that, get discounts and companionship. At the same time, you could make an enemy who will attack you in a certain radius or if you attack them.