One of the benefits of working amidst national security think tanks in Washington, D.C., is that my boyhood obsession of playing "war" never had to go the way of Saturday morning cartoons — it just took on a different form. But in this adult version of G.I. Joes — war games that model how nations will react to different crises, such as invasions, terror attacks, or general nuclear war — the results can be downright terrifying.