I wouldn't bother with rules I would just write a whole bunch of bullshit lying about how the world used to be. I'd make sure it all contradicts itself and has several different stories about the same events.
It wouldn't do too much damage considering that they would inevitably find a ton of books from before.. All depends on how the apocalypse happened I guess.
It wouldn't do too much damage considering that they would inevitably find a ton of books from before.. All depends on how the apocalypse happened I guess.