Alright, so I'm going to fill you in on what happened in MGS3 and Peace Walker, since those are the games that take place before MGSV, so they're going to be the most relevant. I'm going to skip Portable Ops, since it's not really referenced in any of the games. In the early 1960s, a young Big Boss (referred to as Naked Snake at first) was sent into Russia -- with the radio assistance of his support team, which consists of Major Zero, Paramedic, and The Boss (Snake's mentor and closest friend) to find and rescue a Soviet scientist named Sokolov -- designer of a weapon called Shagohod, which can launch nukes just about anywhere in the world -- who wished to defect to the United States. As Snake was bringing Sokolov out, he was ambushed by Ocelot (a reoccurring character in the series). After knocking him out, he was about the escape when Sokolov when The Boss suddenly shows up with various Bond-esque villains and announces that she's defecting to the Soviet Union. She presents the head-villain (Volgin) with a US nuke, and knocks Snake out. Volgin launches the nuke and destroys a Russian research facility. This causes a serious rift between the USSR and the USA, the former of which believes that the nuke was launched by the US. In order to prevent nuclear war and prove its innocence, the US must send in someone to kill the Boss, the head villain, and destroy the Shagohod. Secretly, the US also wishes to steal something called the Philosopher's Legacy, a massive sum of money used by a group called the Philosopher's that essentially kept the world in line for many years until falling apart in the Cold War. They send in Snake, who is still assisted by his support team, which now has a new man named Sigint. Snake is supposed to meet up with one of two Soviet defectors, who was named ADAM, but instead meets up with EVA, who was the other defector. Snake continues on his mission, having multiple encounters with Ocelot and The Boss's various underlings until he eventually reaches and destroys the Shagohod and kills the main villain with EVA's help. He then fights and kills The Boss, an event that molds what occurs in the rest of the series. Before she dies, she gives Snake the Legacy. In the end, after sharing a passionate night of love, EVA leaves Snake, steals the Legacy, and leaves behind a tape recording revealing her as a Chinese spy. In the tape, it is also revealed that the Boss didn't actually defect. She was to infiltrate Volgin's ranks and steal the Legacy for the United States, but when Volgin launched the nuke, the plan had to be radically changed in order to prevent nuclear war. She was loyal to her country to the end, but her country left her to rot and this leaves Snake (who was given the title of Big Boss) a broken man, disillusioned with everything he thought he knew. It's revealed after the credits that Ocelot was secretly a double agent for the President, and that he was ADAM all along. In the intravenous years between MGS3 and Peace Walker, Big Boss, EVA, Ocelot, Zero, Paramedic, and Sigint found the Patriots to bring about The Boss's vision of the future. Eventually, Big Boss comes to disagree with the direction the others are taking and leaves the Patriots, founding Militaires Sans Frontieres (MSF), a mercenary group with Kazuhira Miller, or Kaz. Since Big Boss was such a figurehead, Zero decides to clone Big Boss, and the twins Solid and Liquid Snake are born. About a decade after the Boss's death, Snake is approached by a KGB agent named Zadornov and a little girl named Paz. Paz just wants peace, but Zadornov wishes for MSF to help him remove the US presence from Central America, offering Snake a base for MSF (which comes to be known as Mother Base) and a recording which implies The Boss is still alive. Snake accepts the mission. While in Nicaragua, Big Boss discovers they are transporting nukes. While following the trail of the nukes, Snake meets Chico and Amanda, members of the rebel forces, who decide to help MSF. When he finds where the nukes went, he sees Hot Coldman, a CIA agent, and Huey, a scientist. Hot Coldman is using Huey to create Peace Walker, an AI which is the "ultimate nuclear deterrent" and that the nukes that are being transported are going to be used on Peace Walker, which will then fire to prove that it works. Huey is recruited to MSF, and work is started on Metal Gear ZEKE. Eventually, Snake finds his way to a secret base, and discovers a scientist named Dr. Strangelove, who was the other lead researcher for Peace Walker. It's revealed that The Boss isn't still alive; Peace Walker's AI was modeled after the Boss's thought process and personality. Strangelove joins MSF, and Coldman is killed in a firefight with the rebels. Zadornov, who was planning to use Peace Walker to fire a missile at Cuba to start WWIII is captured by MSF. As Peace Walker is about to launch it's nuke, it's disabled by Big Boss, who then gets one last conversation with the Boss before Peace Walker decides of its own accord to destroy itself to prevent nuclear war. Seeing this, Snake felt that The Boss had betrayed him and everything she did as a soldier by lowering her gun and surrendering her life just for her country. The nuke from Peace Walker is recovered and loaded onto ZEKE. Zadornov then continually attempts to escape, but is caught and killed in self defense by Big Boss. Kaz then calls Snake to the top of Mother Base, where it is revealed that Paz has hijacked ZEKE, as she's an agent of the Patriots. Big Boss destroys ZEKE, and Paz falls into the ocean, seemingly dead. This leads directly into MGSV: Ground Zeroes. I know it's a lot of info to take in at once, but it's all pretty much necessary. The best way to prepare yourself, since you miss out on all of the details and character intricacies, is to either play MGS3 and Peace Walker, or watch a full LP of them on YouTube.

One does not really EXPLAIN the MGS story. It is something that has to be played in order to be understood. Really, MGS3 and Peace Walker before playing Ground Zeroes and The Phantom Pain will cure that one.

It a very long and complex story, but so goddamn good. Seriously, the best thing you can do is get Metal Gear Solid HD Collection for current gen which should be dirt cheap and includes three amazing games (MGS2, MGS3 and Peace Walker). You'll understand the series much better and come to appreciate it a lot more and feel more for the characters. Plus, it will definitely help you with the wait for The Phantom Pain which will come out next year or even early 2016.

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