Just make sure that you DO NOT shoot any POW's. If you shoot one, there is no way that you can win. He is being forced to make the Metal Gear and only he knows how to destroy it. Now doing all this is easier said than done. There are soldiers that you must bypass and tons of pitfalls, lazer cameras, red lazers, scorpions, and many more deadly traps that you will encounter.
Most items are difficult to find.
There are several buildings in Outer Heaven. Most of them have several floors and lots of area to explore. That is one of the factors that makes this game so good. One more thing is that you must be careful not to listen to everyone. Several people will call you on your transceiver.