Similarities between games

The following is a list of similarities between games in the Metal Gear series. The games often have recurring themes, visual motifs and plot devices.

Codec

 * Codec frequencies. Although slightly obvious, Codec frequencies in each game are sometimes shared among similar characters.
 * 140.85 is used for the lead character's commanding officer (or, in the case of Metal Gear Solid: Portable Ops, his second-in-command). The frequency contacts Big Boss in Metal Gear (where it is 120.85); Roy Campbell in Portable Ops, Metal Gear 2: Solid Snake, Metal Gear Solid/Metal Gear Solid: The Twin Snakes, Metal Gear Solid 4: Guns of the Patriots, and Super Smash Bros. Brawl; GW impersonating Campbell in Metal Gear Solid 2: Sons of Liberty; Major Zero in Metal Gear Solid 3: Snake Eater. In Metal Gear and Metal Gear Solid 2, this character eventually betrays the main character and feeds him false information or gives him self-destructive instructions. In Super Smash Bros. Brawl, Slippy Toad hijacks Campbell's frequency if the player uses the Codec while fighting Falco.
 * 140.96 is used to record mission data (i.e. save the game). In Metal Gear Solid, the Tanker chapter of Metal Gear Solid 2, and Metal Gear Solid 3, after saving the game, the character who the player contacts via the frequency makes small talk about a certain field of interest. In Metal Gear Solid 3, Portable Ops, and the Tanker chapter of Metal Gear Solid 2, the save game frequency is the secondary Codec frequency of the character who saves the player's game. Mei Ling also uses this frequency to talk to Snake in Super Smash Bros. Brawl.
 * 141.80 is used for someone whom the lead character looks up to as a mentor or idolizes (or vice versa) who often ends up having a secret identity. In Metal Gear 2, 140.38 is used by Master Miller. In Metal Gear Solid, Master Miller turns out to be Liquid Snake (although it should be noted that Master Miller was killed by the time this revelation was made). In Metal Gear Solid 2, Iriquois Pliskin is Solid Snake in disguise. In Metal Gear Solid 3, The Boss defects to the Soviet Union. In Metal Gear Solid 4, Raiden has become a Cyborg Ninja.
 * 140.48 is used by anonymous callers in Metal Gear 2, Metal Gear Solid and Metal Gear Solid 2; they use pseudonyms on the Codec ("Your #1 Fan", "Deepthroat", and "Mr. X", respectively). They assist the main character via Codec, even though they work against the main character at times.
 * 140.15 is used to contact a female comrade in Metal Gear 2, Metal Gear Solid, and Metal Gear Solid 4.
 * 141.12 is used by Otacon in Metal Gear Solid, Metal Gear Solid 2, Metal Gear Solid 4, and Super Smash Bros. Brawl.
 * 141.52 is used by a female technical adviser in Metal Gear Solid and Metal Gear Solid 2.
 * 142.52 is used to contact EVA in both Metal Gear Solid 3 and Portable Ops.
 * When the main character is fighting with the final boss, the person usually responsible for giving hints of how to defeat the final boss is unable to help.
 * In Metal Gear, Diane does not know Big Boss's weakness when she contacts Snake.
 * In Metal Gear 2, George Kasler thinks that Solid Snake may not stand a chance against Big Boss due to rumors about him becoming a cyborg after the events of the Outer Heaven Uprising.
 * In Metal Gear Solid, Naomi is unable to be contacted due to being under arrest for illegally modifying FOXDIE, and Roy Campbell is detained by Jim Houseman.
 * In Metal Gear Solid 2, Solid Snake is unable to be contacted due to his pursuit of Liquid, although Otacon was available to give Raiden a few hints.
 * In Metal Gear Solid 4, Otacon was busy trying to get some medical aid while Snake and Ocelot were battling, and the Metal Gear Mk II was not nearby.
 * In Peace Walker, Huey Emmerich is at a loss of words on how to advise Snake on how to defeat Peace Walker's second form in the briefing files, and Amanda is unable to help, either. During the boss battle against ZEKE, there are no briefing files available on how to defeat it. In addition, all of the characters are in complete shock about Paz being an enemy spy (or in the case of Huey, that ZEKE is being used against what he actually created it for) to be able to give effective hints (although Miller will give some advice on how to beat ZEKE).
 * In Metal Gear: Ghost Babel, the entire support group is held hostage by Brian McBride.

Main character

 * The lead character being captured, and in some cases, tortured.
 * In Metal Gear, Solid Snake needs to be captured in order to locate Gray Fox.
 * In Metal Gear Solid, Snake is captured by Sniper Wolf and then tortured by Revolver Ocelot, who threatens to kill Meryl, whom Snake had grown close to.
 * In Metal Gear Solid 2, Raiden is captured by Olga. He's then "tortured" by Solidus Snake in a direct recreation of the torture room from Metal Gear Solid. The capture turns out to be a way for both Raiden and Snake to infiltrate Arsenal Gear.
 * In Metal Gear Solid 3, Naked Snake is captured and tortured by Colonel Volgin.
 * In Metal Gear Solid 4, Old Snake is forced to go through a microwave hallway, "torturing" Snake by cooking him alive and occasionally shocking him, and in order to proceed through the hallway, the player must rapidly tap the Action button in a manner nearly identical to the torture scene from Metal Gear Solid , except that they cannot "submit" to the torture.
 * In Portable Ops, Naked Snake begins the game in a cell and is tortured by Cunningham. He is later captured and tortured again.
 * In Peace Walker, Naked Snake is captured and tortured by Dr. Strangelove.


 * The main character starts off with one mission, however, his purpose is actually something different.
 * Metal Gear - Big Boss had the rookie Solid Snake sent to Outer Heaven, hoping to have him captured and feed misinformation to authorities, underestimating Snake's ability.
 * Metal Gear 2 - Snake is intially sent to rescue Dr. Marv, but later on in the mission, he has to recover the OILIX formula and destroy Metal Gear D.
 * Metal Gear Solid – Snake is sent under the belief that he is to rescue DARPA Chief Donald Anderson and ArmsTech President Kenneth Baker and determine if the Sons of Big Boss have the capability to launch a nuclear weapon, and if so, stop them, but in actuality he was sent to infect the Sons of Big Boss, and Baker with FOXDIE so the government can recover the Metal Gear REX without risk of damaging it.
 * Metal Gear Solid 2 – Raiden is sent under the belief that he is to quell a terrorist threat on the Big Shell, but it turns out that he is sent to be the test subject for the S3 Plan.
 * Metal Gear Solid 3 – Naked Snake is dispatched under the premise that he is to rescue Sokolov, and later to assassinate The Boss, Colonel Volgin, and destroy the Shagohod, but in actuality, he ends up helping America to steal the Philosophers' Legacy.
 * Portable Ops - Big Boss is told that he was to try and recruit the Red Army and disillusioned soldiers to his side in order to clear Para-Medic, Sigint, Major Zero, and his own names of involvement with the FOX revolt, but it is later revealed that he was actually supposed to do this so the Pentagon can tarnish the CIA's reputation by having Gene launch the ICBMG into the Soviet Union. This is further revealed to be a conspiracy by Zero and Ocelot to steal the Philosophers' Legacy, who had manipulated the Pentagon, the CIA, Gene, and Snake.
 * Metal Gear Solid 4 – Snake is used to to infect the remaining founding members of the Patriots (except for Zero) with FOXDIE. Snake also destroys the Patriots' AI and brings back Big Boss, a purpose that had been planned for him since his infiltration at Shadow Moses.
 * Peace Walker - Big Boss is enlisted by Ramón Gálvez Mena to drive the Peace Sentinels out of Costa Rica, though Big Boss quickly realizes he is being used to settle a turf war with Russia and the United States. However, it is revealed that the ordeal is a ploy by the Patriots to give Big Boss an ultimatum to rejoin them, or be framed as a nuclear terrorist with the Metal Gear the event led him to develop.


 * Eye patches. In Metal Gear, Metal Gear 2, Metal Gear Solid 3, Portable Ops, and artwork for Metal Gear Solid and Metal Gear Solid 4, Big Boss is seen wearing an eye patch. In Metal Gear Solid 2, Solidus Snake damages his eye and wears an eye patch, but on a different eye. In Metal Gear Solid 4, Solid Snake is seen using the Solid Eye system which he wears like an eye patch over the same eye Solidus wore his.


 * Solid Snake/Raiden/Big Boss landing in a pose near the beginning of the game while disguised in some way, at which point he raises his head and fully reveals himself to the player. This occurs in the cutscene after the player gets to the elevator at the beginning of Metal Gear Solid and The Twin Snakes, at the start of Metal Gear Solid 2 's Tanker chapter after his stealth camouflage fails and when Raiden take the Strut A elevator up to the roof during his half of the game, at the start of Metal Gear Solid 3 after parachuting into the USSR, and in Metal Gear Solid 4 after losing his militia outfit.
 * Drebin and his pet monkey Little Grey parody this landing pose at one point in Metal Gear Solid 4, shattering the drama by belching loudly after posing.


 * A member of the terrorists (usually the leader) impersonates Solid Snake/Big Boss to damage his reputation.
 * Metal Gear Solid - it was Liquid, who looks identical to Snake anyway.
 * Metal Gear Solid 2 - it was Solidus, who like Liquid, is genetically similar to Snake anyway.
 * Portable Ops - it was Gene, who managed to frame Big Boss for stealing the ICBMG/RAXA and organizing a rebellion due to Big Boss's reputation.
 * Metal Gear Solid 4 - Laughing Octopus uses her OctoCamo to impersonate Snake while attacking the rebels. One of which is released so that he will tell the others not to trust Snake.

Cyborg Ninja

 * The return of a major character from a former game disguised as a ninja. The character's true identity is initially concealed. First used in Metal Gear 2 with Kyle Schneider, then Metal Gear Solid with Gray Fox and finally in Metal Gear Solid 4 with Raiden. After appearing as herself in the Tanker chapter of Metal Gear Solid 2, Olga Gurlukovich reappears as a ninja in the Plant chapter.


 * A Cyborg Ninja telling the main character to hurry after saving them. Gray Fox says "Hurry, get away!" after saving Snake from REX, Olga says the same thing after saving Raiden. In Metal Gear Solid 4, Raiden says "Hurry!" to Snake after stopping Outer Haven from crushing him.


 * A unit fights the ninja in an enclosed space. In Metal Gear Solid, Gray Fox uses his stealth camo to surprise a unit of Genome Soldiers. In Metal Gear Solid 2, Vamp slaughters a SEAL Team (while Vamp is not a Cyborg Ninja, this scene is meant to replicate what Gray Fox did in Metal Gear Solid) Olga takes on Ocelot and the soldiers in the hall with the hostages. In Metal Gear Solid 4, Raiden intervenes in Snake's fight against the FROGS.


 * In both Metal Gear Solid and Metal Gear Solid 4, the Cyborg Ninja (Gray Fox and Raiden) has one of their arms cut off and loses an eye (Gray Fox actually loses an eye while Raiden loses a Solid Eye).

Other characters

 * A scientist that the main character must rescue: Dr. Drago Pettrovich Madnar (Metal Gear and Metal Gear 2), Dr. Kio Marv (Metal Gear 2), Otacon (Metal Gear Solid), Emma Emmerich (Metal Gear Solid 2), Sokolov (Metal Gear Solid 3), and Naomi Hunter (Metal Gear Solid 4).


 * A scientist that at some point loses bladder control out of fear: Otacon (Metal Gear Solid), Emma (Metal Gear Solid 2), and Sokolov (Metal Gear Solid 3).
 * Some of Snake's teammates are passionate about their hobbies: Otacon (Metal Gear Solid) is a fan of anime, Mei Ling (Metal Gear Solid) is a fan of classical literature and Para-Medic (Metal Gear Solid 3) is a fan of movies. Sometimes, they will reference something from their hobby as advice to the player: Mei Ling will cite proverbs and Para-Medic will try to relate Snake's situation with a movie she saw.


 * Johnny Sasaki and his bowel problems. Metal Gear Solid, Metal Gear Solid 2, Metal Gear Solid 3, Metal Gear Solid 4. Metal Gear Solid 3 's Johnny is the grandfather of the Johnny from the rest of the series.


 * Some one Otacon cares for/loves dies. Sniper Wolf in Metal Gear Solid, Emma in Metal Gear Solid 2, and Naomi in Metal Gear Solid 4.

Quotes

 * The use of the line "It's not over yet." Originally said by Big Boss in Metal Gear 2, this was later said by Liquid Snake in Metal Gear Solid, Olga in Metal Gear Solid 2, Volgin in Metal Gear Solid 3, Sokolov in Portable Ops, Paz in Peace Walker, and both Snake and Liquid Ocelot in Metal Gear Solid 4. In 4, Liquid Ocelot uses a variation of the quote in Act 4 in Shadow Moses "It's not over! Not yet!" when he arrives in Metal Gear RAY, and gives the exact quote if, when Snake dies in the microwave hallway, the player chooses "exist." Liquid also uses this line Metal Gear Online if he is on the losing team and is killed just before the end of the match, right before rising again and extending the match for another forty seconds. If one of the Custom AI Weapons manages to reboot itself after having its health depleted, it will also say "It's not over yet."


 * In Metal Gear Solid 2 and Metal Gear Solid 3, there is a line of dialog at the beginning of each game where Snake says "Kept you waiting, huh?" This is a very subtle fourth wall break. The line is not used in-game in Metal Gear Solid 4, but Snake does say after the initial 8-minute installation when the game is loaded for the very first time. Instead, Raiden says "Sorry to have kept you all waiting" when meeting with Snake, and when asked about Snake's whereabouts, Otacon says "That guy...always keeps you waiting." Also, in Super Smash Bros. Brawl, Solid Snake says the line at the beginning of every match, and in a trailer. During the Subspace Emissary there is a cut scene fairly early on of Snake's Box. Much later in the game Snake is seen emerging from the box, where he then turns to the camera and says "Kept you waiting, huh?" It is also said in the Snake Tales story External Gazer by an alternate universe version of Solidus Snake, when he says to Mei Ling "Kept you waiting, huh?" One of the CO-OPs messages in Peace Walker is "Kept you waiting, huh?"


 * The use of the line "neither enemy, nor friend." This was said by Gray Fox in Metal Gear Solid, Olga as Mr. X in Metal Gear Solid 2, Drebin in Metal Gear Solid 4 and by Kazuhira Miller in Peace Walker during his phone call to Zero (in this case, he elaborates that he is a business partner).


 * In Metal Gear Solid/The Twin Snakes and Metal Gear Solid 3, both Snakes are tortured and ask a support member to tell them a story to take their minds off the pain they feel at the time.


 * In Metal Gear Solid, Ocelot tells Solid Snake "You're pretty good" after being defeated. In Metal Gear Solid 3, Naked Snake says this when he first defeats Ocelot. Liquid Ocelot says this when he's beaten by Old Snake in Metal Gear Solid 4, which were also Ocelot's last words before his death from FOXDIE.
 * In Metal Gear Solid 2 and Metal Gear Solid 3, someone says the line "There's room for only one Snake and one (Big) Boss." This was said by Liquid Snake upon his departure in Metal Gear Solid 2, and by The Boss upon her death in Metal Gear Solid 3. Big Boss recalls this line in Metal Gear Solid 4, elaborating that "the world would be better off without snakes."
 * In the games, a character (usually one of the "Snakes") mentions swatting down some "bothersome flies" in reference to enemy aircraft. In Metal Gear Solid and its remake, The Twin Snakes, Liquid Snake, when ordering the Genome Soldiers to guard the supply dock of Shadow Moses from Solid Snake's inevitable arrival, tells them that he's going to swat down some bothersome flies, in reference to the two F-16 Fighting Falcons that were launched from Galena Air Base as a distraction method. In Metal Gear Solid 2: Sons of Liberty, Solidus Snake reports that he took care of an annoying fly when communicating with Olga Gurlukovich, in reference to the SEAL Team 10's Sikorsky Sea Stallions, which he had shot down with his Harrier. In Metal Gear Solid 3: Snake Eater, the main character, Naked Snake, will comment when learning from EVA about an RPG-7 being stored in a bunker at the hillside area of Krasnogorje that it should be enough to swat some bothersome flies, referring to the Mil Mi-24 Hinds that were patrolling the area.

Games

 * A scene that demonstrates the boss characters superiority to the main character. Typically they do this by obliterating a unit of soldiers while the main character watches from the shadows.


 * Battles with an aircraft. In Metal Gear, Metal Gear 2 and Metal Gear Solid they were Hind D choppers. In Metal Gear Solid 2 it was a Harrier II jump jet. In the original Metal Gear, Solid Snake destroys the Hind D with a grenade launcher before it could launch. In the latter three games, the protagonist (Solid Snake in Metal Gear 2 and Metal Gear Solid; Raiden in Metal Gear Solid 2) attacks the flying aircraft with stinger missiles. Naked Snake can evade or destroy Hind A choppers in Metal Gear Solid 3, but these are not mandatory boss battles as they were in previous games. Also, Big Boss has to fight off against a flying platform piloted by Cunningham in Portable Ops. In Metal Gear Solid 4 Old Snake can evade or destroy PMCs helicopters but were also not mandatory. However Snake does have to fight Raging Raven who is capable of flying. In Peace Walker, Big Boss must neutralize an MI24A chopper.


 * After the end credits there will be a talking sequence where a major plot twist is revealed. In Metal Gear, Big Boss reveals that he survived. In Metal Gear 2, there is a conversation between Solid Snake, Roy Campbell and Holly White. In Metal Gear Solid, Metal Gear Solid 3, and Metal Gear Solid: Portable Ops, the character doing all of the talking is Ocelot. While in Metal Gear Solid 2 and Metal Gear Solid 4, there is a conversation between Solid Snake and Otacon. In Peace Walker, Naked Snake states to Miller that he is now going to be called henceforth as Big Boss and not Snake, and after the second ending credits, Big Boss announces the creation of his military nation Outer Heaven.


 * Sea insertion is the primary method of infiltration into the enemy stronghold in Metal Gear, Metal Gear Solid, and the Plant chapter of Metal Gear Solid 2.
 * Also, a HALO/HAHO jump was also the primary method of infiltration into the enemy region in Metal Gear 2, Metal Gear: Ghost Babel and Metal Gear Solid 3.


 * A one-on-one fight without any firearms between the protagonist and one of the final bosses in Metal Gear 2, Metal Gear Solid, Metal Gear Solid 2, and Metal Gear Solid 4.


 * A final boss battle where there is a time limit caused by a bombing raid. In Metal Gear Solid, B-2 bombers are sent to destroy Shadow Moses while Solid Snake fights Liquid. In Metal Gear Solid 3, MIGs are sent to bomb the field where Naked Snake and The Boss fight. Although not a boss battle, in Metal Gear Solid 4, Snake has to escape on Metal Gear REX with 5 minutes before the Gekko explode.


 * In one of the final boss battles, there is the added tension that another character may die or may have died as a consequence of the battle. In Metal Gear 2, Solid Snake is forced to fight his former friend and mentor, Gray Fox in a minefield. In Metal Gear Solid, Meryl will die if Snake gives in to torture (as well as having a dilemma when Snake either allows REX to survive in order to allow Gray Fox to live, or use the newly obtained opportunity to fire the stinger missile into the cockpit of REX, but at the same time, kill Fox in the process). In Metal Gear Solid 2, Sunny will be killed by the Patriots if Raiden fails. In Metal Gear Solid 3, Naked Snake's must kill The Boss even though he doesn't want to.


 * A battle against multiple Metal Gear units where the protagonist is armed with only one suitable weapon. In Metal Gear Solid 2, Raiden fights off RAY units using a Stinger missile launcher. In Metal Gear Solid 4, Snake has to fight off waves of Suicide Gekko with the railgun.


 * The final mission is practically a suicide mission. In Metal Gear Solid 2, Snake and Raiden have to defeat all the Tengu Commandos and RAY units on Arsenal Gear. In Metal Gear Solid 4, Snake has to infiltrate the ship Outer Haven which is guarded by FROGS and Gekko. He also has to go through a microwave filled hallway.


 * Often the antagonist is trying to create Outer Heaven, a nation of soldiers, in Metal Gear, Metal Gear 2, Metal Gear Solid and Metal Gear Solid 4. The precursor to it was Army's Heaven in Portable Ops.


 * Often data is stolen allowing the Metal Gear threat to continue even though the current version will be destroyed.
 * Metal Gear Solid - Ocelot steals the Metal Gear REX data and sells it on the black market.
 * Metal Gear Solid 2 - Ocelot's aim in the Tanker chapter is to steal RAY before destroying the tanker itself.
 * Metal Gear Solid 3 - Ocelot stole the Metal Gear plans from Aleksandr Leonovitch Granin, EVA stole the Shagohod data and the Philosophers' Legacy was also stolen.
 * Portable Ops - Ocelot stole the Trajectory Data from the DCI, which contained the Philosophers' Legacy.


 * The main character has a relationship or a connection to the final boss.
 * Metal Gear and Metal Gear 2: Solid Snake - Big Boss.
 * Metal Gear Solid: Solid Snake - Liquid Snake.
 * Metal Gear Solid 2: Raiden - Solidus Snake.
 * Metal Gear Solid 3: Naked Snake (Big Boss) - The Boss.
 * Portable Ops: Naked Snake (Big Boss) - Gene
 * Metal Gear Solid 4: Old Snake - Liquid Ocelot.
 * Peace Walker: Naked Snake (Big Boss) - Peace Walker's Mammal Pod (The Boss)/Big Boss - Pacifica Ocean (Paz Ortega Andrade).


 * The beginning usually has a narrative (done by David Hayter) regarding the event that is taking place.
 * In Metal Gear Solid 2, Solid Snake recounts the events of the Tanker Incident.
 * In Metal Gear Solid 3, A narration is made in regards to the beginning of the Cold War.
 * In Metal Gear Solid: Portable Ops Plus, Big Boss narrates that the war has just begun, even though the takeover of San Hieronymo was halted.
 * In Metal Gear Solid 4, Old Snake notes that war has completely changed.
 * Ocelot usually provides a narration following the credits, with the title of the game displayed during the narration. It always provides information that was currently unknown and is surprising information to the player.
 * In Metal Gear Solid 2, Metal Gear Solid 3, Metal Gear Solid: Portable Ops, Metal Gear Solid: Portable Ops Plus, and Metal Gear Solid: Peace Walker, selecting the start game menu results in a gunshot being heard.

Metal Gear Solid

 * The protagonist, shortly after escaping from his prison cell shortly after being captured, manages to retrieve his items, only to find an extra, unwanted gift that proves detrimental to their mission.
 * Snake, shortly after escaping the prison cell in Outer Heaven and evading Shotmaker, retrieves his belongings to stand an even fighting chance against Shotmaker, only to discover that a transmitter was included in his belongings.
 * Snake, shortly after escaping from the medical room on Shadow Moses, recovers his equipment, only to discover that Ocelot planted a timer bomb among his belongings.

Metal Gear Solid 2: Sons of Liberty

 * Someone who is rescued asks to help but gets denied as they would just slow them down. However, they prove to have more mobility than they seem to.
 * In Metal Gear Solid, Otacon has stealth camoflage and provides snake with rations and ammo.
 * In Metal Gear Solid 2, Peter Stillman reveals that he doesn't really have a prosthetic leg and helps defuse the bombs.
 * The protagonist is given fake data to prevent the real data being stolen.
 * In Metal Gear Solid 2, Solid Snake gives Raiden a fake virus, which Ocelot later steals from him. The real virus was supposed to contain the names of the Patriots.
 * In Metal Gear Solid 3, The Boss plants a fake microfilm on EVA, which she believes to contain the records for the Philosophers' Legacy, after giving it to Naked Snake before her death (as EVA planned to steal it from him after the mission). Meanwhile, Ocelot steals the true information regarding the Legacy for the CIA.

Metal Gear Solid: Portable Ops
Portable Ops contains some references to other games in the series.
 * The relationship between Big Boss and Gene is similar to the one between Solid Snake and Liquid Snake. Gene is the end result of the Successor Project, a project designed to infuse a soldier with The Boss' genes (also a precursor to the Genome Soldier project). Gene even goes so far as to call Big Boss "brother."
 * One of Gene's telepathic quotes during his and Big Boss's climatic battle was almost an exact quote to The Boss's speech during their first encounter in Operation Snake Eater.
 * In Metal Gear Solid, Solid Snake has to take down his former unit, FOXHOUND. In Portable Ops, Naked Snake has to take down his former unit, FOX.
 * Both Portable Ops and Metal Gear Solid feature Frank Jaeger as a ninja who has been experimented on by the enemy's unit as part of a secret project. In both games, Frank is partly insane and determined to kill the main character until he comes to his senses near the end.
 * Also, both Portable Ops and Metal Gear Solid contained an old war buddy of the protagonist who was believed to have died, but in actuality had survived, but was experimented on and also partially driven insane as a result. Also, both in their final appearances give the protagonist advice that has a lasting impression on their character, and in case Python dies in said final appearance, both also have the protagonist calling their names as they die shortly after saying to them "Snake, farewell..." in a particularly gruesome manner (Gray Fox ends up being crushed by Metal Gear REX, and Python ends up exploding and combusting into flames due to his lack of control over his body heat).
 * In Metal Gear Solid 3, there is a backwards interrogation where Colonel Volgin reveals information about the Legacy that Snake did not know. In Portable Ops, Cunningham unintentionally implied that he is actually working for the Pentagon while threatening Snake and his men.
 * The music in general is similar to music from Metal Gear Solid 3, and two specific songs are remakes of songs from Metal Gear Solid 2. The track "Sad Man's Theme" is a remake of "Peter's Theme" and "Evasion" is a remake of "Countdown to Disaster."
 * Big Boss' last action in this game is to salute his comrades. This is similar to his last action in Metal Gear Solid 3 and Metal Gear Solid 4, where he salutes The Boss' grave.

Metal Gear Solid 4: Guns of the Patriots

 * The scene in Act 1 where Snake tries to kill Liquid is similar to their meeting in the Tanker in Metal Gear Solid 2.
 * He hides behind some boxes where he can see Liquid who is in an elevated position.
 * Liquid steals a piece of technology and as a consequence of this Snake and the soldiers are put at risk.
 * Once Snake reveals himself, Liquid makes a speech.
 * Liquid uses a vehicle to escape.
 * Someone comes in and saves Snake from the situation (although in the case of Metal Gear Solid 4, it was on-screen).

Metal Gear Solid: Peace Walker

 * The plan for Big Boss's mission in Costa Rica is similar to Raiden's participation in the Big Shell Incident. Both were ostensibly to remove a threat (the Sons of Liberty in Metal Gear Solid 2, and the Peace Sentinels in Peace Walker), both had initial hints of the true purpose being to mold them into a new legendary hero (Solid Snake for Raiden, and Che Guevara for Big Boss), but were actually intended to achieve far more sinister purposes (testing out AI machines to consider dominion over humanity as well as to sway Big Boss back to the Patriots or frame him if all else fails, and testing whether the Patriots could control society).
 * Likewise, both main characters, when attempting to refuse rejoining/recontinuing with the exercise after learning the full details of the true nature of their mission, are forced by their enemies to do something drastic with the threat of various deaths (Raiden, when learning about the true purpose of the S3 Plan, attempts to refuse their order to kill Solidus, only for them to not only remind him that they'll kill Olga's child, if he refuses to cooperate, and also reveal that Rosemary (and by extension, their unborn child) will end up suffering the same fate), and Big Boss, upon learning the true nature of the Peace Walker project, refuses to rejoin Cipher, only to be forced to fight Paz Ortega Andrade after she revealed that Cipher ordered her to launch a nuke at the East Coast of the United States and then frame MSF for the deed and make them a nuclear-toting cult).
 * The Militaires Sans Frontiere's main base, the Mother Base, bears a strong resemblance to the Big Shell.
 * Similar to Metal Gear Solid 2, the apparent main instigator of the event is also a disgraced member of the government because of his involvement in a mission (in Metal Gear Solid 2, this was Solidus Snake, a.k.a. George Sears, the former President of the United States who resigned due to it becoming public knowledge that he was involved in the Shadow Moses Incident, and in Peace Walker, this was Hot Coldman, the former CIA Director who was removed from this position and exiled in the guise of becoming the Station Chief of Central America's CIA branch for his involvement in the Virtuous Mission and Operation Snake Eater).
 * In both Metal Gear Solid 2 and Peace Walker, an agent of the Patriots mentions taking a Metal Gear back while hijacking it (Ocelot told Scott Dolph, and shortly thereafter Sergei Gurlukovich, that he intends to "Take [RAY] back [to the Patriots]" and Paz Ortega Andrade tells Big Boss that she's taking Metal Gear ZEKE back [to Cipher]). Coincidentally, both Metal Gears had their codenames derived from a codename for the Japanese Mitsubishi A6M Zero line of fighters.
 * In both Peace Walker and Metal Gear Solid/The Twin Snakes, the main character, upon being captured, has to endure up to at least three torture sessions before escaping, and also has the option of escaping early by various devices.
 * Both Portable Ops and Peace Walker has a handicapped person who has ulterior motives in secretly aiding Big Boss despite technically being their enemy, only for their plans to reach an uncalculated setback/divergence (in Portable Ops, Lt. Cunningham, a pegleg, is ostensibly trying to interrogate Big Boss on the Legacy's location, but is later revealed to be intending to help Snake provoke Gene into launching the ICBMG into Russia to tarnish the CIA in a smear campaign. His plan unravels when Big Boss turns against him as well as Gene later revealing that he intends to launch the ICBMG into America, not Russia. In Peace Walker, Galvez, a prosthetic hand-equipped Costa Rican professor/KGB agent, asks Snake to get the CIA mercenary army out of Costa Rica, ostensibly because of suspicious activities. However, it turns out that he was actually using Snake as well as Coldman, his "ally", to take control over Peace Walker and then launch a nuke at Cuba with the intention of framing the United States for nuking one of the Soviets biggest allies to guarantee the Cold War winning in the Soviets favor, as well as killing Big Boss himself to organize more revolts. However, the plan backfired when the FSLN unit turned on him, and a dying Coldman ended up launching Peace Walker anyway as well as leaking the false data to NORAD, nearly causing an all out nuclear war).
 * In Peace Walker and Metal Gear Solid 2, an ally reveals a great truth for the main character. In Metal Gear Solid 2, Rose says to Raiden that she was actually an agent of the Patriots, ordered by them to keep an eye on him. In Peace Walker, Miller reveals to Big Boss that he already knew who Ramón Gálvez Mena and Paz Ortega Andrade were, as well as their allegiance to the CIA, the KGB, and, in the definite case of the latter, to Cipher, and also implied that he was in on their plan.