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.
What is a king to do? A prophesy indicates that a certain person is involved with the death of the king, but the prophesy was unclear as to what role - do they cause it or prevent it.