The planet is Earth but in 2839.
In 2528 a Nation called Robin(s) took over earth and enforced a strict government after a deadly WW3 which ended in a Nuclear Doomsday. 90% of the Earth is inhabitable or atleast radioactive other 8% is controlled by the Robin(s) 1% by the Rebell(s) known as The Federal Force (TFF) the rest 1% is unkown.
The following major citys are in the hand of Robin(s) (Note the citys are renamed): City 0 (Capitol), City 1, City 2, City3, City4, City5, City6…City 17. The TFF City called Zeus the outterbases/outposts are under the codename of Tiger (East Coast); Eagle (West Coast) and Mexico ( the most souther one [about the middle of the US.]). To get the hang of the Robin citys, they have daily curfews, armed military personals patroling 0/24 and frisking suspicious people.
Each city has its own border guarded by the military. Police does not exist everything is run by the military. While the TFF has only 1 City and 3 outter base/outpost. The area where the RP takes place is the United States (you can go further btw). Between each Robin’s city moves a hyper train with 1000 km/h with fence alongside the rail. The Capitol City has a 25m wall around it which has Auto-Turrets and also guarded. If you read this far just letting you know its an Open RP 
The TFF is located to the north of the US, while the Robin(s) stretched from East to West.
Most of the United State is non-radioactive or just a bit but every military personal (Robin) wear a gasmask while outside of a building. There are Military Checkpoints alongside the roads.
The technology is MT (ModernTech).
I think thats a fair ammount of information to start Roleplay-ing might add more, if you have any question ask freely