Jamais Vu

Jamais Vu was an event that occurred at an unknown point in time, in an alternate universe.

Prelude
A Soviet commuter jet ended up crashing in the ocean near the United States Prison Facility on the southern tip of Cuba, with something coming out of the wreckage before it sunk. Telecommunications at the base were blacked out for a full 24 hours, yet when they were fully restored, the only communications afterwards were a suspicious "conditions normal" and nothing afterwards. It was later confirmed that the base had been overrun by unknown life-forms only identified as Body-Snatchers that kill people and steal their identities.

Finding the events suspicious, a CIA contact hired the private military company, Militaires Sans Frontières to investigate and exterminate any and all Body-Snatchers at the base. MSF's leader Big Boss was briefed about the event by his lieutenant, Kazuhira Miller. As the subject matter and mission was far beyond even Big Boss's capabilities, they ended up hiring a time-travelling cyborg, Raiden, to partake in the mission in their stead, as his cybernetic body made him immune to Body-Snatchers taking him over and the conditions of the area. In exchange, MSF would supply Raiden with the XOF patches they had collected in a prior operation.

The mission
Sometime later, during a storm at 00:01, MSF arrived via chopper at the prison facility. Big Boss then showed Raiden a watermelon containing a XOF patch on it to remind him that this was their payment should he succeed. After Raiden activated his Augmented Reality visor, he then stood up. Big Boss then offered Raiden his sword, but he declined, instead being content with the firearm he had received. Miller then reminded Raiden that most of the Marines on the base are most likely Body-Snatchers inhabiting human bodies, and as such not to expect many survivors. After arriving at the jump point, pausing only to load his gun, Raiden proceeded to jump out of the chopper. The chopper then departed, although not before Miller relayed to Raiden that the fate of the world is in his hands, also telling him to mark the personnel to separate the soldiers from the snatchers.

Raiden found a soldier near the watchtower. Although the soldier was not a Body-Snatcher, Miller nonetheless ordered Raiden to interrogate the soldier for anything he knew, finding the man suspicious. After learning from the man the location of all the personnel across the base, Raiden managed to spot a Body-Snatcher. He then killed him. After hunting down and killing all 8 confirmed Body-Snatchers on the base and neutralizing the non-Snatcher soldiers, Raiden prepared for extraction from the MSF chopper. Before he could get himself extracted, several waves of Body-Snatcher reinforcements unexpectedly appeared, forcing the chopper to keep its distance while Raiden wiped them out, including several manning various vehicles and choppers. Upon confirming all of them were wiped out, Raiden boarded the chopper and departed from the area.

Aftermath
As promised, Raiden received the XOF patches, with Miller considering meeting Raiden again in the future. Miller then debriefed Big Boss after the crisis was over, although the Body-Snatchers' origins were unable to be determined. Miller then expressed hope that they didn't have anything bigger planned, and that the whole situation seemed like a bad dream.

Behind the scenes
Jamais Vu is the extra op mission that is exclusive for the Xbox 360/Xbox One versions of Metal Gear Solid V: Ground Zeroes. It is unlocked by collecting all the XOF patches in the main game.

The cassette tape "Jamais Vu" can be found on one of the rocks near the shore. It is found in the same place with its PlayStation 3/PlayStaion 4 equivalent mission, Déjà Vu. The tape contains two songs: "Ambush" from Metal Gear Rising: Revengeance, and "Pleasure of Tension" from Snatcher.

There are several references to Metal Gear Rising throughout the mission:
 * The chopper that delivered Raiden to the base has the Platinum Games logo on the fuselage of the chopper.
 * The opening song for Metal Gear Rising is heard in the background as Raiden arrives at the intrusion point.
 * During the pre-mission briefing, several watermelons were shown in the chopper, with one of them having an XOF patch attached, alluding to the watermelon-cutting demo for Metal Gear Rising 's development predecessor, Metal Gear Solid: Rising, as well as the cutting up of watermelons in Metal Gear Rising itself.
 * Miller will tell Raiden that he has a self-repair unit but can't steal extra units from the Snatchers.
 * Miller will mention Raiden's skills with a blade.
 * During the final moments of Jamais Vu, the Hammerhead boss theme can be heard as Raiden holds off the advance of the remaining Body-Snatchers as well as during the credits.
 * During the post-mission debriefing and rewards tally, the menu/post-mission tally theme from Metal Gear Rising can be heard.
 * After Raiden managed to wipe out all of the reinforcements for the Body-Snatchers, Miller can be heard imitating George's line "Cowabunga." Alternatively he will imitate Boris Vyacheslavovich Popov's line "Yes Raiden! Horosho!" or Kevin Washington's line "That's my boy."
 * If the player beats the mission on Normal and Hard difficulties, they will unlock the White Armor and Commando Armor, respectively, which were pre-order skins and later DLC content for Metal Gear Rising.

The player can locate various logos for previous games in the Metal Gear series, adorning various walls, buildings and the MSF helicopter. Viewing the logo of each Hideo Kojima-directed game with the binoculars and then using the radio will cause Miller to comment on the games, including the graphic details for each one, and imitate characters from each one (specifically, Big Boss in Metal Gear [though he will say "Miller here" despite not appearing in that game; with his advice being to stay away from enemies with his subtitles being in the style of the MSX2 game ], himself in Metal Gear 2: Solid Snake [specifically, his advice that right or wrong don't matter on the battlefield], Otacon's question about whether Solid Snake was an otaku as well as well as Snake telling Otacon "If we make it through this, I'll tell you!" in Metal Gear Solid, Solid Snake's advice to Raiden in Metal Gear Solid 2, The Boss's declaration of making their best ten minutes of their lives in Metal Gear Solid 3: Snake Eater, Drebin's slogan in Metal Gear Solid 4, himself in Metal Gear Solid: Peace Walker), and in the case of Metal Gear Solid V: Ground Zeroes, on the advancement of technology and imitating Otacon's line in Metal Gear Solid 4 about pondering what they'll "come up with next." However, those not directed by Kojima, will cause Miller to have trouble reading the game's title or recalling anything from them. In addition, a rifle found in the admin building's storehouse is equipped with a light that allows Big Boss to remove the Kojima-directed games' logos, similar to the removal of the XOF logos in the main game's opening, but not the others. Upon erasing all of them, Miller will confirm their disappearance, although he will also stated that the markings will "live on inside you." In addition, Kojima will thank the player "for all [their] support."

The narrative at the beginning says the following: "Our galaxy consists of some 300 billion stars. Around half are orbited by planets, and it is said that on average, conditions on two of a star's planet are suitable for life. No great leap of imagination is needed to believe the universe must be home to a myriad of life forms. But what sorts of intelligence would develop on these worlds? That is truly beyond our imagination. What's more, we cannot say that our universe is the only universe. At the quantum level, until a wavefunction collapses upon observation, Schrodinger's cat is alive and dead as a superposition of states. The moment observation occurs, these two possiblities branch into separate worlds, with the universe continuing to split infinitely. If the universe splits without end, it's possible it could eventually recreate scenes from the past. And if those things played out differently, it wouldn't negate what happened in our reality - a paradox would simply mean another future. The following is one possible story in one possible universe, born of paradox, after paradox, after paradox..."

The narrative before the chapter, as well as their comments about XOF patches, indicates that the mission takes place in an alternate universe where MSF not only didn't end up devastated by XOF, but also wiped out the XOF unit and succesfully rescued Chico at least.

In psychology, jamais vu (French for "never seen") refers to the phenomenon of experiencing a situation that one recognizes in some fashion, but nonetheless seems very unfamiliar.

Kiefer Sutherland was credited as Snake in the level's end credits, even though Snake never actually spoke at all, and was not the playable character. However, Snake's voice is used if Raiden interrogates an enemy soldier though his voice does not sound human.

The game acted as the second time in the overall series that Big Boss and Raiden interacted, the first being Metal Gear Raiden: Snake Eraser on the Secret Theatre option of Metal Gear Solid 3: Subsistence. Coincidentally, both instances also involved time travel on Raiden's part.