Introduction

In a nutshell, this is a post-apocalyptic world where everything was the same as in the real world up to about 1983, when the Cold War escalated into WW3. Atomic bombs wiped out the headquarters of the military super powers and caused an economic collapse, followed by resource shortages and epidemics.

The war eventually died down as everyone started forgetting what it was about in the first place and no one had the means to maintain an organized military force anymore. People formed smaller communities amidst the ruins of their civilizations and regressed to less technologically advanced lifestyles. A large portion of the world population was wiped out.

State of the Economy and Society

With the absence of functional infrastructure, whole industries died and individual craftsmen gained more significance again, as did simpler means of travel and agriculture. Industrial infrastructure is being rebuilt nowadays, but only slowly. Scientifical efforts have been thrown back by years and lack the means to progress in a meaningful way. People and their settlements have become more self-sufficient and insular communities have formed. Superstition and holding tightly onto traditions are more prevalent than they have been in a long time.
Instead of large corporations, small family businesses and merchant guilds have emerged to handle trade and supply flow. On the other side of the spectrum, mercenary has become a very popular occupation, as laws of all sorts are only enforced locally and in most places, especially out of the communities' jurisdiction, killing or robbing someone has become only a matter of morals, not a punishable crime. Being able to fight and defend oneself is a skill that most are taught at a young age.
Currencies exist, but inflation and volatile exchange rates have led to people frequently paying in kind or with services instead of carrying around a truckload of money. Many communities have introduced their own currency for themselves and their close allies. Being rich in one town does not necessarily mean that two towns over, you will be able to buy a single loaf of bread.

Transportation and Mobility

While horseback or simply walking has become a very popular way of travel for short and medium distances, longer distances are a challenge. Motorized vehicles, while a common sight, are challenging to maintain for the average person. They are mostly owned by businesses or military organizations, or wealthy individuals.
Trains are popular as well since they are a semi-public way to travel. You just board the train and don't have to worry about maintaining it yourself. But not every place is covered by the rail network and some operators charge steep prices for their service.
Ships and planes are also options for long-distance travel, but mostly used for freight instead as their upkeep is expensive and complicated. Operators usually charge passengers unaffordable prices. Only in rare cases, cheap "remaining seats" are offered. This makes these ways of travel hardly accessible for anyone but the wealthy, turning far-away places like other continents into an unrealistic destination for most.

Agriculture

Generally, local supply is handled by farmers. Inter-community trade allows for goods to reach places where agriculture is not viable. But there is no real means to transport perishable products to far-away places. Food is therefore usually sold at local farmer's markets.
Machines have limited availability; tractors and the like are common, but vehicles like a combine harvester can only be spotted at bigger farms; more archaic tools are the norm.

Governments and Geopolitics

Country borders are barely relevant anymore. The names of the former countries are mostly known, as is their history for the most part. But dividing the land into approximate regions is the norm nowadays. Governments have been re-formed in a rudimentary manner, but their power and influence is limited to their respective community: Large cities do no longer exist and are left in ruins, with only some districts being inhabited in a way that is functionally similar to towns. The average person lives in a town with a population of less than 5000 citizens, more commonly less than 2000. These towns have mayors or councils and simple administration, as well as dedicated law enforcement in the shape of hired guards.
A lot of people live in nomadic clans instead of towns. They travel around, visiting several towns, usually as mercenaries or merchants. They tend to have a route that loops itself, frequenting the same towns and trading posts repeatedly. Many clans quickly gain a reputation among the locals that way.
Inter-community relations are often tense, with feuds being very common. Good relations and alliances do exist, though.