In the Afterfall universe, World War II ended much differently than it did in the real world. The Axis powers created an atomic bomb before the Allies did, which enabled them to reach an armistice rather than surrendering. What followed was a Cold War much different than the one we remember.
It was eventually broken by a nuclear exchange that caused most of humanity to head below the surface of the earth. The backstory for Afterfall really is intriguing and could have lent itself to any number of interesting stories, especially since the game itself is based in Poland, a central area for this conflict.