The background assumption is that the 1991 coup  in the Soviet Union was a lot more aggressive and successful than the historical version (which lasted two days and led to the breakup of the Soviet Union). In this alternate history a much wider section of the KGB and the Soviet Army backed the coup, and the State Committee on the State of Emergency was able to reunite the Soviet Union with force of arms following a demands by Helmet Kohl (and an increasing military presence) to renegotiate the Polish border from the Oder-Neisse line . Moving rapidly, insurrections also occurred among hardline communists in the former Warsaw pact (such as Intermovement  in the Baltics), calling for Soviet intervention. Ignoring international protests, in 1992 the Soviets retook their former territories in the Eastern bloc, despite majority civilian opposition.
As Soviet forces reached the borders of Germany, NATO responded with a counter-offensive which was devastating on both sides. Salients were won and lost with a speed reminiscent of Napoleonic cavalry movements but on a scale of hundreds of kilometers rather than metres. When a particularly aggressive Soviet salient pushed through Erfurt then Frankfurt and Saarland, the French acted to protect their territorial integrity - by using tactical nuclear weapons, specifically Pluton missiles  from Oberhoffen-sur-Moder and Belfort.
The Soviet response was immediate. President Gennady Yanayev stepped down
to manage public affairs, Marshall Dmitry Yazov was replaced by the younger and more competent Yevgeny Shaposhnikov and interior minister Boris Pugo became President. In a strategic move, the Soviets launched attacks on U.S. military satellites, severely weakening NATO intelligence.
A massive nuclear counterstrike is launched against the U.S. and its NATO allies, including large numbers of nuclear-armed Soviet satellites, generating global electromagnetic pulses , destroying most unshielded
equipment. From the oceans, Soviet submarine-launched ballistic missile (SLBM) warheads strike against nuclear facilities in the United States. For their own part, the United States responds with intercontinental ballistic missiles (ICBMs) against the U.S.S.R and attacks from B52 strategic nuclear bombers.
The nuclear conflict brings the rest of the world into the action; India and Pakistan, long in opposition, engage in a conflict with the use of nuclear weapons and Israel takes the opportunity to create several glass sculptures in capitals that were potential threats. China, hitherto staying out of the conflict, comes on the side of the Soviet Union following the French attack, and in particular with North Korea as that government comes into conflict with South Korea, Japan, and the United States (and eventually Indonesia and Australia). The United States takes the opportunity to use a number of tactical nuclear weapons against Cuba to destroy any possibility of a deep counter from that source.
The effects of the war were already predicted and well-known in the scientific community . Following the initial devastation that destroys almost all major urban centres globally, followed by massive radiation poisoning, followed by a nuclear winter that lasts two years, and then a complete collapse in economic productivity and infrastructure. The only semblance of government that is left behind is small local authorities, jealously guarding their resources. Technically, the war continued and certainly there is a great deal of behaviour that suggests this, although over time such things as rank and seniority fell into complete disregard, By 1996 the war had exhausted itself as an organised command-and-control practice on a strategic level, with no central government really being capable of engaging in command and control.
By 2000, the global population has been reduced by fifty percent and eighty percent in urbanised Europe and the United States. GDP has been reduced by well over ninety percent; as predicted it was a new dark ages. There is very little in terms of electronics that operate at all. Working vehicles and fuel are, of course, in very high demand, although wrecks are common. There is some small scale agriculture. Currency exists where governments exist, but in the main they have been replaced by local script and items of utility. For the past four years, the player-characters have eked out an existence of sorts in war-devastated Poland. Like so many others, they now represent a small band for hire, made up of mixed forces, trading their military abilities and equipment for food and fuel.
Suffering shortages however, word has reached the PCs of a city to the south which has managed to organise itself and is serving a central point for trade where there is a local government that strictly enforces a public peace. It is calling itself the "Free, Independent, and Strictly Neutral City of Kraków with its Territory" .