There’s a good article on the New York Times on the themes of Metal Gear Solid 4. It never reaches any conclusion, obviously.
Is the Sisyphean mission of Solid Snake — to rid the world of a robotic nuclear tank called Metal Gear — a parable about the futility of war or about its necessity? A critique of America’s domination of the global stage? A metaphor for the struggle between determinism and free will? If the creator of the Metal Gear Solid series, Hideo Kojima, has answers to these questions, he isn’t telling.
Have a read.