[Nyororin]

I would look to see what groups were working toward the reinstatement of their thought up set of rules (these groups would definitely appear) then side with and support the one that most suited me...
And if there were none, form such a group myself.

There are plenty of examples of what happens when there are no "rules". Someone comes along, makes rules, and then enforces them. Usually it is whoever has the most firepower.