I decided to join in on this. below is a Screenshot from the Demo Version of DEFCON. The timer at the bottom is the victory countdown from when theres only a certain number of missiles left (20% or lower for the Demo Version). I don't have the money to buy the full version but would recommend it as the game is well done.
The secret to winning against the computer is timing and to attack the moment they launch from their silos as they have no defence against missiles then. The compter 'waits' to position their missiles and I think a human player would realise how fatal that is.
After playing it for two weeks So far the "winning" side almost never comes out with anything less than 40-50% losses minimum. There was one exception, where only 3% got killed, but that was a fluke because I got all the enemies silos before they even launched. The Full version has settings to do it on a bigger world map in real-time, which you could do over a few hours. it's tempting to buy it just to do that once for the sake of realism. it can do fasters speeds, the longest game I've played so far would have been 6 hours in real life. By the end of this game, the Americans had only 2 million out of 100 million people left. I "won" with about 50 million survivors out of 100 million people.
By a combination of music, background sounds and the abstract looking map, the designers managed to create a very eerie atmosphere. if you settle into playing it and don't rush, the sense of "thank god this isn't real" stays with you. the fact people wanted to do this for real is crazy.