Nuclear war, zombie outbreaks, meteor strikes, economic collapse, alien invasion, no matter how it happens an apocalypse makes for a unique and engaging setting to run a campaign in, even for a jaded GM.
Here’s a few quick tips that can make a good zombie or other post apocalypse game a great one, and keep the group coming back (from the dead?) for more.
Elves use nature as strength and borrow from the trees to keep them living. An elf out of the forest for more than a day begins to die and within 3 days is dead without borrowing the strength of nature.