Balance of Power: The 1990 Edition was a special edition release of Balance of Power sometimes referred to as Balance of Power II). It was released simultaneously on five platforms in 1989 after the original achieved many sales.
The 1990 edition adds more countries, advisors to help out the player, a new "multi-polar" level that allows countries to generate events of their own (such as declaring war on other countries), and a few miscellaneous features. However, with the ending of the Cold War, interest declined, and there have been no further follow-ups or clones.
Source: Wikipedia, "Balance of Power (video game)", available under the CC-BY-SA License.
From the back of the box:
It has been several years since the release of the original Balance of Power. In that time the political voices in the world have changed dramatically.
Now, in response to popular demand, master game designer Chris Crawford gives us Balance of Power: The 1990 Edition - a new and enhanced game of global politics and power struggles. Featuring a new multipolar level, this game allows 80 countries to ship weapons and troops, and fight wars; your challenge as a superpower is to monitor their policies and use your influence - at times to the point of diplomatic crisis - to protect your interests.
- Covers eight years, from 1989 to 1997
- Simulates real world political struggles in the nuclear age by allowing interaction among 80 countries (formerly 62)
- Allows 4 levels of play, from Beginner to the complex Multipolar level.
- Utilizes a vast and updated database and faster processing capabilities
- Icludes a four person on-screen "crisis advisory" group forcounsel in crises
- Enhanced with non-nuclear war feature for smaller countries
- Includes both 1- and 2-player games