"Solid Snake's storyline has ended with Metal Gear Solid 4. But there's still a lot more when it comes to Big Boss' storyline. The Cold War was a time where people, neither good nor evil, were manipulated by various factors, and they became good or evil. The same goes for Liquid Snake, and we'll get to see just what happened to him."
In the infiltration, Snake overhears an argument between Huey Emmerich and Hot Coldman, the CIA station chief in Central America. Coldman outlines the basics of nuclear deterrence theory, where mutually assured destruction will prevent nuclear powers from ever actually using their weapons. The flaw in the theory though is that humans are left in charge of the decision to retaliate, which can lead to an exploitable weakness that doesn't discourage a first strike. Coldman seeks to have a computer controlled weapon, dubbed "Peace Walker", that can guarantee a retaliatory strike, thereby rendering first strikes as suicide. However, in order to prove his theory, Coldman needs to make a nuclear strike to prove Peace Walker's capabilities. Huey is outraged that Coldman is going to use his creation to launch a live nuclear weapon and tries to convince him to stop. Coldman dismisses Huey, forcing the wheelchair-bound scientist to fall down a flight of stairs.
Snake comes to Huey's aid, recruits him to MSF's cause and then hurries to catch up to Peace Walker. However, he is attacked by a Shagohod-like unmanned vehicle dubbed "Pupa". He destroys the Pupa, but not before Peace Walker is extracted via helicopter and taken to the Costa Rica-Nicaragua border for final launch preparations. Huey advises Snake to seek out the main AI researcher on the project, Dr. Strangelove. He also offers to help build a Metal Gear for MSF.
As per Huey's advice, Snake heads north to seek out Dr. Strangelove. On the way, he discovers an escaped prisoner named Cécile Cosima Caminades, a French ornithologist who was captured when she was seeking out Quetzals in the Costa Rican jungle. Snake soon realizes that she is the one who made Paz's tape of The Boss, but is surprised when it turns out that Paz and Cécile have never met. Snake sends Cécile back to Mother Base and then infiltrates Strangelove's lab. Inside he finds the Boss's horse and Strangelove. Strangelove confronts Snake, angry at him for assassinating the Boss 10 years earlier. She shows him her creation, an incomplete AI reconstruction of The Boss's personality known as the Mammal Pod. Strangelove goads Snake into trying to destroy it, but Snake finds himself unable to.
The Mammal Pod and Strangelove are from the lab as Snake is attacked by the Chrysalis, the flying AI weapon which had attacked Snake and the Sandanistas earlier. Snake shoots down the Chrysalis and destroys it before heading north to intercept Peace Walker. When questioned on his ability to complete the mission by Miller, Snake insists that he will be able to go through with it and destroy the Mammal Pod, although his insistence is not entirely convincing. After so many years of wrestling with the meaning of The Boss's defection, Snake wants answers.
Snake pursues Peace Walker to another CIA base, but is attacked by mercenaries and the massive Coocoon AI weapon. Snake overcomes these foes and then makes his way into the heart of the enemy base. Here, he sneaks his way to the Mammal Pod, but hesitates when he has the opportunity to destroy it. He tries to get the AI to tell him why The Boss betrayed her country, but it is unable to answer. Outraged that the AI can't give him the answers he needs, Snake finally tries to destroy it, but too late - Coldman, Strangelove and the CIA forces surround him and take him captive.
Snake infiltrates the CIA base, but is shocked to discover that Soviet troops are occupying it. He continues onwards as MSF forces launch an attack on the base, hoping to provide Snake with support so that he can get to Coldman and stop Peace Walker. Snake makes his way to Coldman and his captive, Paz, but is surrounded by Soviet soldiers and CIA mercenaries. Coldman gloats that he has already input false launch data into Peace Walker and that it will strike Mother Base as soon as he inputs the confirmation code. Before he can do so, Gálvez arrives. He reveals that his real name is Vladimir Alexandrovich Zadornov and that he has been in league with Coldman all along... before ordering the Soviet soldiers to turn on Coldman. Coldman is incensed as Zadornov reveals that he wants Peace Walker to fire at Cuba in order to spread anti-American sentiment throughout Central and Southern America, bringing the Soviets closer to winning the Cold War. Zadornov then forces Paz to shoot Coldman twice, leaving the man slowly dying from the wounds, before ordering Strangelove to change Peace Walker's target to Cuba. He then mockingly congratulates Snake, stating that his actions have helped the communist revolution in Nicaragua, that his death at the hands of the "CIA" would make him a hero in the same vein as Che Guevara, and that his death would make him into a fraud like The Boss.
However, before he can complete his plan, Amanda leads the Sandanistas to attack the base and take Zadornov captive, stating that they won't be puppets of the KGB anymore. Amanda and the Sandanistas thank Snake for giving them the strength to return to their home nation. Having presumably prevailed, Snake gets an apologetic Strangelove to take him to Peace Walker so that he can finish off the Mammal Pod and end this crisis. Strangelove states that all she really wanted was to learn the truth of The Boss's final mission.
Hoping to prove himself right in the end, a captive Coldman secretly inputs the authorization code for Peace Walker before succumbing to his wounds. This causes Peace Walker to become active and begin launch preparations, while also relaying false-launch data to NORAD. Miller informs Snake that they are unable to stop the transmission and that if they do not hurry then the US government will have to decide whether to launch a nuclear "retaliation". The only way to stop the signal would be to destroy Peace Walker itself.
Snake moves to destroy Peace Walker to prevent nuclear holocaust. He is able to stop Peace Walker from launching its own payload at Cuba, but is unable to stop the false-launch transmission. Hacking into NORAD's communications, Huey discovers an extremely tense situation as the assembled heads of the US government are preparing to go to DEFCON 2 and launch a retaliatory strike at the Soviet Union. Realizing that Coldman's gamble was going to literally blow up in their face, Snake orders Huey to patch him through to the Pentagon where he uses his reputation to convince the Chairman that the launch data was false. However, the other officers aren't convinced and they overpower the Chairman, forcing the retaliation to go through.
With the situation becoming critical, the Mammal Pod opens on its own and Snake climbs inside to disable The Boss's AI. In spite of this, the signal continues to be relayed, and Strangelove theorizes that The Mammal Pod's functions must have been transferred to the mech's second AI unit, the Reptile Pod, which is responsible for Peace Walker's mechanical processes. In desperation, Snake tries to destroy Peace Walker once again, but the machine stands upright and begins to walk into the ocean. The Boss's voice begins to sing out as Peace Walker drowns itself and the false-launch transmission to NORAD is replaced with peace symbols, stopping the government heads from launching at the last possible second. Snake, Miller and Strangelove all watch on as Peace Walker destroys itself, proving that The Boss willingly went to her death. Snake salutes for his former mentor and then casts aside the bandana that he had taken from her ten years ago, stating that he believes that by putting down her gun ten years ago, The Boss betrayed him. As a result, Snake finally accepts his title of "Big Boss".
In the game's epilogue chapter, "Outer Heaven", MSF builds up its power in the aftermath of the incident. With Strangelove's help, Huey completes Metal Gear ZEKE for MSF. Miller recovers Peace Walker's nuclear missile and equips ZEKE with it in order to provide MSF with its own deterrent against world powers that might object to them. Zadornov also escapes from captivity seven times, prompting Snake and Miller to believe that there is someone on the inside aiding him. On the seventh escape, Snake encounters Zadornov hiding aboard Mother Base and then kills him in self defence. Immediately afterward, alarms go off in the base as somebody activates ZEKE.
Snake hurries up to the deck and finds that ZEKE has been hijacked by Paz, who reveals herself as a deep-cover agent of "Cipher". She declares that she will take ZEKE back to her "masters". She outlines Zero's basic philosophy of information control, which she insists is the only way to bring about worldwide peace. She offers Snake the ability to join with Cipher once again and be their deterrent against anyone who tries to stop the creation of this future. Snake refuses, which causes Paz to prepare a nuclear strike against the east coast of the US, which will frame MSF as a terrorist group and allow Cipher to seize control through fear, bringing about their plans either way.
Snake battles Paz and severely damages ZEKE in the battle. An explosion throws Paz from the mech's cockpit into the sea, and Snake presumes that she dies from this. Miller hesitantly reveals that he was aware of Cipher and of Paz's true loyalties, much to Snake's chagrin, but that he was using them as a means with which to grow MSF to where it now was. Thanks to Cipher, MSF has effectively pioneered a new kind of business venture. Snake warns that the world is going to fear them now and that enemies will be coming for them soon.
That said, Peace Walker's narrative is quite enjoyable on its own merits and is easily one of the more unique entries in the series' canon. In some ways, Kojima also restrains himself and puts out a far more streamlined narrative. For example, it's really nice to see Coldman explaining his entire agenda in his introduction rather than saving this for later as part of a big plot twist and exposition dump as Kojima usually does. This can also be applied to Zadornov's introduction, as Snake and Miller realize that he is a KGB agent within the first few minutes. Even this reasonable amount of restraint is enough to reduce some of the narrative fat which plagues Kojima's stories and makes Peace Walker quite a bit easier to follow.
The game's non-linear design does create some narrative issues though. Foremost amongst these is that we have no idea how long a time period the game takes place over. Based on the way that the main missions flow, it seems like it can't be more than a couple weeks for the main part of the game, with anywhere from a few months to a year passing in the epilogue chapter. This is obviously problematic once you realize it though, because that means that MSF expands to a vast size and builds a fully-featured offshore Mother Base in a matter of weeks. Then, they build their own Metal Gear from scratch in less than a year. The obvious intent here is for the player to miss this little chronological detail, but once you become aware of it, it is a rather nagging issue.
I must also say that the section of the game where Coldman activates Peace Walker has to rank amongst the most intense sequences in the entirety of the Metal Gear series. The tension just builds and builds as the situation grows increasingly more hopeless and Snake struggles to do absolutely everything in his power to prevent nuclear Armageddon. This is all capped off with a surprisingly impactful sequence where The Boss's spirit sacrifices herself once again in order to save the world.
That said, The Boss's AI is the point where the game's story strains believability. It doesn't make a lot of sense and the game doesn't do a good enough job to justify its existence. Somehow, Strangelove is able to piece together a nearly-perfect AI personality using old mission data about The Boss, and yet she isn't able to complete it without knowing whether The Boss sacrificed her life for her country? The fact that she needs Snake's confession to finish this last piece of The Boss's personality never really made a lot of sense to me, because Strangelove already assumed that she knew the answer. Could she not have just programmed her own suspicions into the AI just to test whether it would work (it also doesn't help that the process used to get this AI functioning is not expounded upon at all)? It also creates some strange issues about Peace Walker in the game's climax, when the game heavily implies that The Boss's soul possesses the Mammal Pod and sacrifices itself a second time (in fact, Huey says in a rather schmaltzy manner that Peace Walker is acting "with its heart" rather than its mind, which is just ridiculous). I can understand the reasoning for these decisions - it works on a symbolic level for the AI to be a representation of The Boss's soul, but on a narrative and logical level none of this makes any sense and it nearly derails the entire plot for me.
It is also quite interesting that the ending causes Snake to turn on The Boss and accept that he is her successor. The reason he gives is because he believes that by putting down her gun and allowing Snake to kill her, she gave up on her ideals as a soldier. While it isn't directly stated, I believe that this is confession is meant to show the flaws in Big Boss's interpretations of The Boss as an individual and The Boss as the symbol which he has been building up an ideology around for the past 10 years. As an individual, it seems that The Boss's will was a desire for a world without conflict. However, in Snake's mind, it seems that he has subscribed to The Boss's will as a world where soldiers are valued, can fight for a greater good and where they live for nothing beyond the mission they are given. Considering that divergences in interpretation of The Boss's will drive the conflict between Zero and Big Boss throughout the Metal Gear saga, this seems to me to be a hint that the "good guy" doesn't even have it right. Snake has thrown himself so far into a predefined worldview in the name of his former mentor that, when confronted with the reality of her ideals, he turns on the source his entire ideology.
Not surprisingly, Peace Walker's primary theme is an exploration of the nature of peace and deterrence theory. While it is not exactly subtle in its methods, this makes for some rather interesting discussions on human nature. Using deterrence as a major theme was particularly fascinating to me. I actually "developed" an understanding of deterrence as a child when I was around 10-13 years old. I was wondering why we haven't had an open conflict between major superpowers since the Second World War, when it occurred to me that the threat of nuclear attack made open war an unappealing prospect. As a result, I theorized that we wouldn't see another World War until a missile-defence system was developed which would render nuclear strikes worthless, thereby making conflict viable once more. While obviously this was an overly-simplified view of international politics, it does hold true to the basics of deterrence and I was able to appreciate the game's premise quite a bit.
Coldman's views on deterrence are quite interesting and his plan actually does make just enough sense that it might have worked if he had managed to complete his plans. Having a 100% guaranteed retaliation makes mutually-assured destruction more than a threat - by having the capability to strike, they end up rendering all of their nuclear weapons useless. However, Coldman also believes that humans are incapable of launching a retaliatory strike on their own volition, a notion which Kojima declares patently false in the game's climax as the US government nearly sets off the end of the world. The other big issue which the game seems to raise about deterrence is that everyone seems to equate it with peace. However, based on The Boss's idealized vision of world peace, this does not mesh with her desire for peace without borders - deterrence, after all, still requires two aggressively opposed nations who are just not particularly interested in launching into all-out conflict for fear of total annihilation.
One of the more interesting and subtle uses of peace in the game though is in regards to the Sandanistas. Shortly after being introduced to Paz, the physical embodiment of peace in the game, Snake comes across Amanda and Chico, who are fighting a revolutionary war to wrestle control of Nicaragua from the American-backed regime. This creates a rather complicated picture which suggests to me a questioning of when conflict is justified. The Sandanistas cause is suggested to be a righteous one in opposition to the Somoza regime, with Amanda and Chico fighting for a cause that they so deeply for that they are willing to lay down their own life to achieve it. The game also makes numerous references to Che Guevara for similar reasons, suggesting that while peace may be the desired (if unnatural) state for mankind to achieve, there are times where fighting is necessary and justified.
Also tying into the theme of peace, Peace Walker is unusual amongst Metal Gear games for being really on-the-nose with its characters' names. The most obvious examples of this are Paz and Kazuhira, both of whose names translate to "Peace". However, it is not exactly subtle that both of them end up betraying their namesakes - Paz turns out to be an illusion, whereas Kaz is a businessman whose ultimate goal is to spark the war economy. The fact that both characters with the name "peace" end up betraying their namesake seems to tie into this quote from Immanuel Kant which features in the game and is brought up by Paz at one point:
Paz and Kaz aren't the only characters with meaningful names though. Amanda Libre's name is very apt (it basically translates to "lover of freedom"), while Chico is literally a character descriptor (it means "young boy"). Hot Coldman is also so obviously a symbolic "name" that they could have called him "Cold War Jackson" and had the same effect."Peace amongst men living alongside one another is not a natural state. On the contrary, the natural state of man is that of war. War manifested not only by open hostilities, but also by the constant threat of hostility. Peace, therefore, is a state that must be established by law."
Strangelove's name is also pointing out, although for somewhat different reasons. First of all, it is incredibly obvious that her name is a reference to Dr. Strangelove or: How I Stopped Worrying and Learned to Love the Bomb, a film which, in itself, has a lot to do with the game's themes. Her name also foreshadows that she will become Hal "Otacon" Emmerich's mother, since his namesake comes from 2001: A Space Odyssey, both films of which were directed by Stanley Kubrick. However, as obvious as the film reference explanation for her name is, the game tries to go even deeper and pass it off as a reference to her sexuality. This is a really weird way to try to twist the name in my opinion and kind of underscores the series' weird approach to "queer" sexuality. Vamp is the closest parallel - he's obviously named Vamp because he's designed to be like a vampire, but then it is explained in-game that the name comes from him being bisexual (it's a slang term, you've probably heard it in Def Leppard's "Pour Some Sugar On Me"). I actually like Strangelove as a character and find her rather fascinating, but the handling of her sexuality is clumsy (she's a bit of a misandrist and sexually assaults most of the game's female cast) and trying to highlight it in her name doesn't help all that much (although that's just my take on things - there are more positive assessments of the sexualities of the series' characters which are worth checking out).
Peace Walker's treatment of women in general is about as juvenile as ever. Aside from the aforementioned clumsiness about Strangelove being a lesbian, the game also goes out of its way to make awkward jokes about Paz and Cecile. For example, in Paz's introduction you can zoom the camera in on her to give an x-ray vision of her in her underwear. There's no real justification for this other than for it to be "funny", but it's also really awkward considering that at this point in the game we're supposed to believe that Paz is a 16 year old girl. Paz also ends up in her underwear on a couple other occasions, like if you get an S-rank in the Date With Paz mission and when she steals ZEKE for some reason. Cecil, on the other hand, has basically no bearing on the game's plot, but exists to be little more than an inside joke and some eye candy (in her introduction, if you zoom in on her cleavage the game will make a cartoonish popping sound).
On a more positive note though, Amanda Libre is a pretty great female character. The camera actually seems to respect her and she has a pretty great character arc as she learns to take responsibility as commandante of the Sandanistas. She even saves Snake's ass in the end. Plus, while the game hints at there being some sexual tension between Snake and her, it is left as a mutual respect in the end and doesn't end up being the defining aspect of her character in the slightest. Amanda is a great example of how Kojima can write a strong, interesting female character without objectifying her in the process, which is something that he does on a distressingly infrequent basis.
While Peace Walker largely avoids the crappy kind of "George Lucas cameos" that afflicted Portable Ops*, it does have one extremely egregious offender: Huey Emmerich. It strains belief that both Big Boss and Solid Snake would coincidentally meet up with an Emmerich and become friends. This whole addition is clearly meant to be a big shout-out to the fans, but it just totally rubs me the wrong way and feels more like bad fan fiction than the actual narrative (although The Phantom Pain would do its absolute best to fix all the problems that this bit of indulgence created...).
I'm also not a big fan of the way that cassette tapes are used in this game. They are only accessible before missions, where you get a list of tapes from each character. However, the game doesn't let you know how long these tapes go on for - most briefing tapes are around a minute at most, but there are longer ones which can easily take 10 minutes or more per tape... and all of this is just keeping you from playing the mission you have been queuing up to play. As a result, if you're like me then you're going to quickly just ignore all of the briefing tapes, which is unfortunate because they do have some very informative background story info and some hilarious jokes. The tapes about the Box Tank and Snake believing in Santa both had me laughing out loud, and the tape which reveals that Cecile's name translates to "KOJIMA IS GOD" in Japanese had me in stitches. There are also tapes by EVA, Strangelove and Paz which are all extremely key to appreciating the game's narrative, but are hidden in the cassette tapes section and can easily get missed. EVA's tapes are perhaps the most important to the overall franchise, detailing a ton of information on The Boss, her fateful mission into space, The Philosophers and corruption in the CIA. Strangelove's fill in more info on The Boss and her mission to space, but they also are important for understanding her motivations and make her a significantly more sympathetic and tragic character. Paz's tapes are also important to understand the twist about her being a villain, and actually make her far more sympathetic in the end as well.
I'll be honest - when Peace Walkerfirst came out on the PSP, I didn't dig it all that much. I got sick of the armoured vehicle battles and the AI grinding and never actually saw the game's real ending (in part because I didn't realize that it had one). I even tried to play through the game once in the past when I bought the HD collection, but I ended up pouring all my time into Snake Eater instead. Having gone through Peace Walker again though and reached the real ending, I do have to say that my estimation of the game has improved considerably. The game has a pretty great story and its gameplay is fun for the most part, although it could have been improved with less frustrating boss encounters and more challenging regular troops. It's also too bad that they didn't use the HD collection as an opportunity to bring Peace Walker in line with Guns of the Patriots' gameplay.
*Kaz gets a free pass for being so essential to the narrative, for not really resembling his former portrayals and for ultimately making Kaz's fate in future games even more surprising and impactful.