You're viewing a single thread.
The Long Earth by Terry Pratchett and some guy who's name is harder to remember.
An inventor uploads a schematic to the Internet for a cheap, easy-to-assemble device that lets anyone (or almost anyone) "step" into parallel earths. A nearly infinite stretch of untamed wilderness sees people abandoning the polluted, crowded, government-run Old Earth in search of new opportunities. The catch: No iron or iron alloys can "step" across, sending these new earths back to the bronze age.
Also: Zeppelins that are also reincarnated Buddhists that are also the first true machine intelligence; robot cats; libertarian communes; sapient nonhuman primates; sapient nonhuman non-primates; radioactive ziggurats; space programs to parallel moons; and grumpy survival chicks.
Stephen Baxter
The premise was better than the execution, but I've definitely been curious if you could use the world stepping premise in an RPG in a compelling way.