>>96771622
Interdimensional Travel.

Different dimensions, altered physics, strange biologies, alien cultures, and the like. a real emphasis built in to setting and system. Even a slightly closed cosmology focussed on alternate timelines would be a big step.

D&D-style inner/outer/transitory is bizarrely restrictive despite intentions, and 5th somehow got more lazy with the same restrictions. MtG seems to no longer give a fuck about worldbuilding (despite starting to branch out with Planeswalkers...and then stopping) and Planescape is incredibly shallow despite it's general premise.both are a huge letdown. Most non-WotC systems I've read either copy D&D's architecture or they're like L5R where realms exist but they're off limits 95% of the time and/or made for a very specific scenario. I'm also aware of the 9001 sci-fi games that let you build a planet on the fly, but I believe that there are fundamental differences in how planes or planets interact with story, setting, and players.

The closest I've seen to an interest and in a pseudo-roleplaying format is a handful of CYOAs where the author either named a few off the top of his head with a brief overview or a couple where you randomize (or choose) a handful of tropes and figure out how they come together as a tangible reality.

Honorable mention to DCC, who's gonzo open source approach has fostered a slew of classes, races, adventures, items, etc mentioning Isekai portal bullshit (or phlostigon disturbances) but nobody has actually tied it all together in an actual setting or story that I know of.

>inb4 soulless faggots start posting police call boxes