I actually didn't know there was an MMO so I looked it up. They're quite different.
Here's the wiki page on the Rifts tabletop game: http://en.wikipedia.org/wiki/Rifts_%28role-playing_game%29
It's got a fair bit of info on the setting, but still just the tip of the iceberg. (There's like 60 world and dimensional sourcebooks that have been published over the years, so it feels like a pretty near limitless treasure trove of material.)
Re: Rifts-based DR
Here's the wiki page on the Rifts tabletop game: http://en.wikipedia.org/wiki/Rifts_%28role-playing_game%29
It's got a fair bit of info on the setting, but still just the tip of the iceberg. (There's like 60 world and dimensional sourcebooks that have been published over the years, so it feels like a pretty near limitless treasure trove of material.)