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.
Next time you're contemplating a horse variation, but don't want to get too dramatic, how about a Zorse? An offspring of a zebra stallion and horse mare. In nature they are infertile, but in a fantasy world, not necessarily. They are also known to be extremely cantankerous.
"It soon became apparent that zorses are not the most easiest of the equine family to get along with." -- Trainer Pat Parelli, on working with zorses