Years ago in High School I had a massive migraine headache that lasted for five days.  I stayed home from school and ended up going to the emergency room.  But in those five days I had the chance to play the hell out of this game.  The concept is a lot like the Terminator and the Matrix.  It's a distopian future wasteland where the machines have taken over the world, humans have retreated underground and there's very little atmosphere left on the surface to support human life.