The 1990 game I initially ran ended due to nuclear war, yes. The world situation became incredibly tense for a variety of reasons, and thus a random chance of nuclear war emerged if players didn't diffuse the tension. Instead, the tension was ratcheted up even further (such as China deploying troops at the Taiwan strait and in the Korean DMZ.)
This next game, "War on Terror," is set in 2001 and being run by someone else, and plays more like a "game" compared to my Balance of Power games.