First off, it is a thrid person stealth action shooter game. So way back in day Naked Snake gets sent to Russia, His mission is to save Sokolov, a Russian scientist building a metal gear called "Shagohod". It can launch nukes from Russia to america. Not good. So the game ends with him killing his only friend called "the boss" and him receiving the title "big boss" , Shagohod is destroyed, and the main love interest betrays him. I am sketchy as too what happens until metal gear solid 1. Which is mostly pointless information for number 5. Big Boss goes around killing people, hiring mercenaries, and tries to end the world as we know it. Throughout most of the games he is "evil". However Naked Snake, Big Boss, Punished Snake, they are all the same person. He tends to be a main character in much of the series. Good luck learning/sorting this soup of story. Been working on it for 13 years now.