Strange World Blue doors allow a form of time travel and provide access to future worlds. Complex and sometimes poorly understood natural laws control and in most cases prevent paradoxical changes in the time stream. It isn't generally possible to visit one door, read the paper, and then go to a door to an earlier era and buy a winning lottery ticket. In fact, you might not even remember reading that future paper in the first place.
Most of the doors nearest Nexus City open to two particular future eras: 2044 and 2638. As usual, there are plenty of exceptions. 2044 is the era of the CURBIT Technology Cops and the Unique super-powered mutants. 2638 is the era of the star-spanning Hundred Suns.
The Tech Cops, officially the "Confederacy of Urban Regions, Bureau of Illegal Technology" (CURBIT) has been established shortly after the SpacePort Wars of 2021. Mankind had long scared itself with the threat of interstellar invasion. When a lone Zyan ship appeared in orbit, it contained refugees and rebels, and no planetary attack capability. Mankind didn't know this, and the few space-faring powers vied to be the first to contact the aliens.
Nobody had an orbiter ready for launch, and it didn't take long before the twelve operational space ports were either under attack, in flames, or in one unfortunate case, dusted with radioactive fallout. Then, after a French team backed by the European Union made first contact, the cruise missiles began to fly. The targets were laboratories and universities, not population centers. The insanity ended with a series of military coups, the elevation of isolationalist governments in Europe and Japan, and the emergence of a coalition of city states that spanned the Americas, Middle East, and Africa. Over the next fifteen years, this coalition prospered, in part from reverse engineering that lone Zyan starship.
Nobody was sure whether it was the indiscriminant deployment of weapons of mass destruction, something biochemical from the Zyans, or coincidence, but this was also the era of the Unique -- humans with incredible, seemingly magical super powers. Things never looked better.
The Tech Cops were formed to police new, destabilizing technology. No longer would nations, or worse, individuals be allowed to have nuclear weapons. If any new aliens arrived (and by then everyone knew they were out there) it would be CURBIT who made first contact. Invent a new plasma laser? Better tell the Tech Cops. Invent a new stock market predicting computer? The Tech Cops would be paying you a visit.
Then the rest of the Zyans arrived, and they were looking for the refugees and especially for the rebels.
To add a little spice to this simmering mix, a super-powered villain named Professor Ruby invented (or according to some, stole) a reality zipper. He powered it up, and found himself in the Strange World Blue tunnel. Ruby smuggled in illegal tech for years before CURBIT even knew what was going on. They eventually controlled most contact with the Strange Worlds -- but never all. It was a constant game up catch up.
CURBIT maintains a well-staffed consulate in Nexus City. The current consul is Captain Blackout.
Little is known of the long period between the 21st and 27th centuries.
Mankind obtained faster-than-light star drive from the Zyan as part of the Treaty of Iapetus in AD 2052. Scientists, sages, and Toolmasters tinkered with the expensive, inefficient FTL tachyon fields and improved performance a hundredfold. By 2060 interstellar wormholes allowed nearly free transport between distant star systems.
Proximity didn't seem to matter; a ship approaching one wormhole could traverse a thousand light years in a week, while another ship approaching a different wormhole could traverse a mere two light years in six months. Interstellar empires, federations, and alliances sprang up quickly. Some intersected with existing alien spheres of influence. In 2104, the wormholes connecting to Earth began to fail. Ships that tried to make a wormhole run to the home world never returned. Zyan FTL drives were used to make a direct flight home. None returned to report on conditions. Collections of inhabited stars that were still connected to working wormhole nets formed independent states of a few dozen or a few hundred stars.
One of these wormhole networks, dubbed "The Hundred Suns" consisted of vast urbanized planets, frontiers, several alien home worlds, as well as immense artificial stations called "Plexes." The Hundred Suns also had connectivity to a much larger universe through over sixteen hundred Strange World Blue doors.
The Hundred Suns includes terrestrial worlds or moons, alien worlds where humans must use environmental suits, and vast orbital habitats called "Plexs."
Here's a map of a portion of The Hundred Suns and some circa 1991 rules and geography for the videotex-era Hundred Suns Starquest campaign (operated by the author using 8 TRS-80s wired to 8 phone lines into his Houston, TX apartment).