Dimensional travel. The idea that for every choice, two or more different worlds are created. There are some who say that time travel is unfeasible, but switching dimensions could well be within the realm of possibility. It's a favorite them in sci-fi literature whether it is true dimensional travel, a "what if?" story, or a combination of the two, as in Harry Turtledove's Guns of the South. There are myriad short stories and novels that are widely read and enjoyed. With Steve Jackson's GURPS as the premiere multi-genre RPG, it was only natural that the game look into this area. Way back in third edition, the Infinite Worlds setting was one of several campaigns featured in the GURPS Time Travel book. With fourth edition, the campaign gained it's own title book.
The basic premise of the setting is that dimensional travel was discovered in the early 21st century by a pair of scientists. It is now the mid 21st century and the UN has oversight of the project. Thus far, only one other world is known to have dimensional travel technology. However, their dimension is on a different "quantum level" than ours and they cannot reach "Earth Prime" directly. However, Earth Prime frequently has conflicts with them in the "grey zones." I'm not going into a indepth discussion of the quantum levels an how they work--suffice to say that history can be altered in these other world and push them up or down in level. Thus, a world could be made unreachable to Earth Prime by a shift.
There are literally an infinite number of Earths out there. Some are relatively benign and ripe for exploitation. For instance, there are "Eden" worlds were man never developed and thus available for colonization (as in the failed television series Terra Nova) or harvesting of natural resources. There are the 'Reich worlds" where the Axis powers won WW2. Most are technologically stagnant or have even developed in to a hell world (q.v.) after Japan and Germany squared off with nuclear weapons. At least one, Reich 5, is on a par with Earth Prime in technology; they do not have dimensional travel and we hope they never do! (Not quite true; but the main Nazi hierarchy does not have the knowledge.) Visions of a more lethal trans-dimensional Iron Sky come to mind. There are "hell worlds" where a nuclear war or some other catastrophe wipe out civilization. In my own games, I coined the term "Romero worlds" for one that have undergone a zombie apocalypse! there are literally hundreds of possible worlds!
One campaign I've always wanted to run is based not on the UN's Infinity Patrol but based instead around the U.S. government's "Worldgate Project' buried deep in Cheyenne Mountain. Sound familiar? Now, while the UN does have oversight of dimensional travel, several governments have access to conveyors. Supposedly, nothing occurs with UN oversight, but we all know how tricky governments like the U.S., Russia, Japan, and even the UK can be (Torchwood Project, anyone?). So, I have some ideas about the U.S. finding some worlds and keeping them secret from the U.N. Possibly coming into conflict with the Reich 5 Ahnenerbe plot, working to bring about civil rights on a Dixie world or two, that sort of thing. And all the while trying to keep clear of the Infinity Patrol!
Another interesting idea in the Infinite Worlds setting is that it is possible to have (alternate) figures from history recruited into the organization. And, since the worlds move at different relative speeds, it s possible to have say, Niccolo Machiavelli as an agent. This allows an out of place place, out of time character like Teal'c from Stargate: SG-1. I did start this game once, but it fell apart before the first session. I had one player create a police officer and his K-9 partner recruited from a Romero world who had survived for several months after the Rise. I was really looking forward to that characterization in play.
All-in-all, the fun comes from creating new worlds that SJG has not published yet while playing with all those tropes and changing them up.What about a world where things went badly for the U.S. in the Pacific and. while Germany is defeated, the Empire of Japan and the U.S. sign an armistice? A Dixie-world where slaves who would fight for the Confederacy were freed leading to full civil rights for blacks in the 1920's; meanwhile, in the defeated North, blacks are despised and persecuted and the U.S. embraces communism in the 1910's. Conflict galore in that one. It's all about playing with history and seeing how players react; and it's fun, creative fun.
Until next time, gentle readers, think of the possibilities!