How hard would it be to add a quest system down the road with Bandits, or bandit bases that encompass more than one building?

Example: Somewhere in the world the player has family they need to rescue. They have X Days to travel across the zom-scape to reach them and the family npcs don't spawn until the player arrives at the destination. If they fail, the family spawns as zoms. For added stress the timer can be HIDDEN from the player.

Or the players could take a job from NPCs to gather X, Y, and Z or go off and take care of raiders in another location.

In the sandbox settings you could set which family members would spawn, parents, spouse, kids, friends, ex's, rivals etc etc.

Example of a safe zone: Specific regions could randomly spawn a 'safe zone', an area that spawns walls and fortifications under the control of a certain clan with a mix of 'frightened civilians' that can be either friendly or hostile to the player... or perhaps each clan has it's own 'main base'. Once the base is destroyed then they stop spawning.

I know just enough coding to know that this would NOT be easy, and I want to attempt it myself sometime, but until then...