Honestly, the one thing people should be disputing about post-apocalypse games is why it is people would even be scraping by to survive in the first place. We’re social animals and would band together out of necessity, and knowledge and high technology wouldn’t simply go away simply because half the population turned into zombies and started eating everybody else.
Just hike to the nearest town or something. Read a book. Build a cistern and some aqueducts or something. People have literally been doing just that for thousands of years so why would it be hard for people to do it in modern times?