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.
Recently, agents of a necromancer's guild known as the Guild of Morticians have been seen slinking around the graveyards in the metropolis of Jeffsport. They have been seen with many small undead creatures, leading to speculation that someone may be digging up the corpses and selling them to the Guild of Morticians. The Jeffsport Civil Authorities Office and various splinter groups thereof, including the famous Blue Lampsmen (the Jeffsport city guard), have issued a bounty of 100 silver pieces for information leading to the capture of whoever is selling the corpses to the necromancers, and a 30 gold piece bounty on any member of the Guild of Morticians.