Rifts to Gamma World ; Suitability Series Vol.3
Rifts World Book 2 : Atlantis
Anyway here is my latest installment in the Rifts to Gamma World series.
Well this book has some of the same problems with conversions to Gamma World that Vampire Kingdoms did. Namely high magic and supernatural content. If you run that kind of Campaign your in business! If not much less of the book will be of use to you. First off for the uninitiated, in Rifts; Atlantis returns to Earth (it was in dimensional Limbo somewheres) but the Atlanteans are not at home! Instead its ruled by a nasty Being/beings known as the Splugorth! Enormous Tentacled Eyeball Thingies from another dimension. They are using Atlantis as a Multi-Dimensional Slaver Market.
As far as Gamma suitability goes; you could use them/It as a truly nasty Mutant Overlord/s type, maybe some kind of extremely powerful mutant sea creature? I can't see really bringing Atlantis into a "traditional" Gamma campaign . But having a unique Arch-Villian, based on the Splugorth, running some kind of coastal slave trade would be cool, you could even run some Slave lords adventures (using the old AD&D Slave Lords series as inspiration).
Delving deeper into the book one finds a small host of Splugorth minions some are usable with Gamma with some serious tweaking. The Blind Warrior women could make for a neat minion mutant race.The Splugorth slave stock section has a few interesting critters, several of which are humanoid bird types (great mutant animal potential). There is a large magic section ,of course, but I won't go into that here. Where the book really shines is the Parasites & Symbiotic Organisms section, lots of "stealable" material, the picture of the Chest Amalgamate is worth it alone!! Makes the Symbiotic Attachment mutation take on a whole new meaning. : )
There is even one parasite the slavers use to make their slaves docile, and therefore controllable.Moving further one finds Rune weapons (kinda munchkin) and some weapons and vehicles (most of which are beyond "traditional" Gamma's scope).
Additional Input by Thorn:
I've got this book, and it does have some good stuff in it. The one I would consider best for GW though would be the Stone Master. Probably would import them into the game as a sub-species of man, maybe miners stuck underground that develop their mutations from the radiation and chemicals seeping through ground water,etc. And the ones that travel and live on the surface would be the true stone masters, while the ones underground would be their mentors etc.