makes a game about the US putting nukes under Major European population centers

I had to look up what you were referencing, and found this .

Operation Greenlight is fictional, but it's based on America's use of "Green Light teams" during the Cold War. These were cells of special forces personnel who were given small tactical nuclear bombs called "B-54 Special Atomic Demolition Munitions," or "backpack nukes." Green Light teams were deployed in Warsaw Pact countries and instructed to blend in with the local population. In the event of a Soviet invasion, they were supposed to sneak behind enemy lines and detonate their bombs.

The Americans went as far as actually deploying Green Light teams throughout Europe. The existence of the plan came to light in 1984, and the U.S. had recalled all operatives and their bombs by 1989.