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.
A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for 'study' by the Guild. The party's presence will be 'requested' for this expedition.