I played a post apocalypse FR years ago near the release of 3E where Shar had rended the Weave and assasinated Mystra with the help of Cyric. Seriously, I wonder who stole my notes . . .
Anyway because my players had played FR a lot before and I had shunted them into the future through a spell, seeing the world they loved corrupted and destroyed was awesome. Tons of drama and great comedic potential.
Dannyalcatraz;4730809Other readings: 1) Terry Brooks' [I said:Shannara[/I] books are post-apocalyptic fantasy set in our world, which is being made more clear now that Brooks has linked them to his Word & Void trilogy and his Genesis books.
2) S.M. Stirling's novels of The Change are set in a P-A version of our world that has a more low-fantasy feel. They are also linked to his Islands in the Stream of Time books.
)I've started one campaign with an apocalypse before. I took Eberron, FR, Greyhawk and a dozen or so nameless worlds, smashed all of them together in a planar catastrophe and scattered the fragments of all the worlds across an endless sky, linked by flowing threads of rivers winding thru the air.
That was a fun one, and my players really enjoyed the whole feel of the place.
Gamma World is my second love RPG behind D&D. I would bring it back in a heartbeat if I thought it would sell. I love the real world tech meets mutant/fantasy elements.
I'd love a new Gamma World in the style of the 1st and 2nd editions.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.