DEFCON (http://www.introversion.co.uk/defcon/), inspired by the venerable War Games movie.
Anyone tried it? By the looks of it, the game seems wickedly fun.
I've played through the tutorial, which ends with a full war that is damn chilling to play through.
Great game, but it could use a better developed single player format, I'm in a different timezone to most players so I need that and it's really an online game.