OK You will be the leader of a small village after a grate disaster. You will have say 20 people who are living in your community and it is you job to protect them from well the harshness of the world out side.
It will involve building up your community and gathering resource to help protect them and keep them alive.
Food, weapons and building stuff will all be essential.
As you community grows, through people joining you or having children, so will your land every one needs (well wants) a bed and its your job to keep them happy so they don't revolt.
I also like the idea of you jumping into a first person role and going out to salvage with say a posse.