On this alt, Earth was left with a situation like the Pax Draconis, but limited to the surface of the Earth. Now, 10,000 years later. The World is divided into 25 regions, each run by a Draconic overlord.
The language and culture of Earth is pretty different from Prime Earth. the Physics of this world is the same. So certain engineering principles, biological and ergonomic principles remain the same. So Doors, cars, machines, weapons will all be Similar to known examples. Just descended from a different line of thought.
Here the area covered by Bowling Green and other small towns and farms is covered by a modern city. This city is where the Draconic Emperor of the Earth makes his throne.
Although, the technology is roughly comparable to 2013, in one area it has lagged badly. Weapons. Since the Draconic Overlords do NOT fight among themselves, military technology is an afterthought.
So the Imperial Guard are security guards with clubs to beat down people who get out of hand. These guys are good hand to hand fighters. They get practice from various insane individuals who want to get close to and harm the Emperor.
Ranged weapons are bows and cross bows, used for hunting.
Any engineer will understand a firearm, once the principles are explained. These items were just never developed on this alt. The closest they get to war is going into the back country to flush out gangs of bandits.
These people have littered the Solar System with unmanned probes and serious robots for exploration. Their computer and electronic engineering is good.
Buty this has all developed through paths we're not familar with, since war has effectively been banished from this world.
The gate has been locked from the other side for almost 10,000 years. The Dracnic Emperor has almost forgotten it was there. An archeology minded person might see the remains of ancient guard posts at Mammoth caves.
Guarding the portal is WHY the Capital city was put here to begin with. The Draconics and their friends on Earth were attacked and almost destroyed by Mellor forces and then left alone ever since.
If PCs are identified as coming from the Fringeportal, the Draconic Emperor will call for them and ask them to come give him an update on what's going on. Dependind on the PCs reaction, they may make an enemy of these people, or they may gain an ally.
If things go well, the Draconic Emperor will offer support to Fringeworthy and start trying to find his own.
If thing go poorly the next visitors will discover that the portal chamber has been walled off with reinforced concrete.
If the Draconics are all on Earth, what's happening in Space? That's a good question!