This page contains the game's main story plus some extras.
In the year 2020, a strangely younger Solid Snake is dropped off at a giant skyhigh facility floating above the pacific ocean with the mission of stopping the supposed fabrication of a new Metal Gear. Snake makes his way through the bottom of the ship and rescues two hostages, the hostages go into a panic and confirm the fabrication of a Metal Gear but also say they do not want to find out anymore about it, when asked why they say that a third hostage went to explore more about the operation and got sent to be executed not long before Snake was dropped off.
Snake asks for directions to where the third hostage was taken and ends up in the center of the ship where he finally finds the third hostage, Snake bursts in and saves the third hostage but in the process alerts the rest of the ship about his presence. Snake takes the third hostage and takes her to the warehouse area where she reveals her name, "Tammy", she also reveals that she was a reporter that was kidnapped after acquiring certain knowledge of the Metal Gear that was being fabricated there.
Tammy thinks that the one in charge of the operation is the magnate, and owner of the skyhigh facility, "Bardo Caspianne", as many clues point to him, Snake agrees and sets out to find Bardo, only to find he's gone into hiding somewhere in the ship.
Snake and Tammy team up to find the blueprints of the Metal Gear so they can destroy it but they find that the blueprints have been kept hidden from the rest of the crew and that the only one who knows their location is a higher-up only known as, "Brad" by the other crew members.
Snake sets out to look for Brad and finds him, however when he confronts him he loses the duel fast and is about to be finished off until a hostage who escaed starts making noise and distracts the guards. Snake then stands up and throws a punch at Brad's face while he's not looking but no blood comes out and the mark looks more like a dent, Brad just laughs it off and throws Snake to the ground, knocking him out.
When Snake wakes up he finds out the man from before, "Arnold Randam", took him in while he was unconscious, Snake thanks him and sets out to find Brad but he's stopped by Arnold, who reveals that Brad was a TX-11 cyberdroid dug up from the Outer Heaven incident, which Snake can't seem to remember. Snake interrogates Arnold about how he got info about Brad but Arnold says he can't remember and that h just feels like knowledge about Brad just popped into his head as soon as he was taken hostage.
Snake and Tammy recruit Arnold and keep searching for the blueprints until finally finding the area where the Metal Gear is being built, Snake tries to infiltrate but he's spotted by a man known as "Dashing Cheetah" and sent to be punished until Tammy creates a distraction and frees Snake.
Snake wonders what's the next step until Arnold suggests cutting the power to make a distraction, Snake goes to the Power Generator Area only to be ambushed by a heavily armoured soldier wielding a chainsaw, Snake defeats him and cuts the power where he is spotted by Brad once again but before he can attack Snake the alarm sets off once again markng that Arnold has sneaked in.
After escaping Snake is told by Tammy that Arnold was kidnapped, so Snake sets out to where the hostages are held only to be ambushed by soldiers. Snake defeats them all and runs to the jailcell area only to find that the soldiers were a distraction so that they could move Arnold to another place, Snake runs back and Tammy tells him Arnold's location, he goes there and finds Arnold who reveals that he got the blueprints to the Metal Gear until Arnold is taken away once again.
Snake chases after Arnold only to find he was locked up and he needs a keycard from a higher-up to open up the chamber, so Snake decides to look for one. Snake walks into an area where weapons are fabricated and tested only to be ambushed by Dashing Cheetah again.
Snake confronts Dashing Cheetah but he flees and Snake falls into a trap where he is captured and used as a target for testing the new "Hind D", which was recovered and repaired from the Shadow Moses Incident, but Snake escapes and takes down the helicopter.
Snake chases after Cheetah once more but Cheetah tricks him and Snake ends up in the laboratory area, Snake looks around only to be caught and poisoned by the crew members there, Snake is woken up by Tamy who tells him that he was injected a strong type of poison and that only a higher-up with the codename of "Jumping Piranha" has the antidote. Snake starts looking for Piranha but doesn't find him anywhere, around this time he also meets up with Brad again who taunts him and tells him that if he doesn't hurry up his "little friend" (Arnold) will be thrown overboard to his death.
Tammy locates someone who may know about Piranha's location and Snake tracks him down, the man reveals his name, "Kyle", and explains that Jumping Piranha is hidden away in his own "chamber", when Snake asks what he means Kyle explains that Piranha prefers to stay alone in a special room filled with pools and aquatic wildlife.
Snake goes to the coordinates given by Kyle only to find out it's a trap when he's ambushed by "Twin Shots", two brothers who pilot turrets together. Snake defeats them both and keeps on going until finding a room filled with spy technology, including some prototypes for a future device named "Spyder", which is a remote-controlled robot spider that can spy on people by sneaking into rooms, Tammy suggests using the Spyder to see through the vents and Snake decides to go with that plan.
After going through the vents by controlling the Spyder Snake finally finds the chamber Piranha is in and sets out to find it, once there he sneaks his way inside and finally confronts Piranha. After a long duel Snake wins and uses the antidote to cure himself from the potion, around this same time Tammy digs through some files and it is revelaed that the Solid Snake you play as isn't the real Solid Snake, but a child soldier from Zanzibar who later became part of an experiment to raise a clone of Solid Snake.
Snake sets out to confront Dashing Cheetah next, and finally finds him at the bottom of the ship, Snake tells him about how he killed Piranha and got the antidote and Cheetah flees until finally luring Snake to a place near the back of the ship where he finally engages in a duel with him. Snake wins and a weakened and highly injured Cheetah gives him his keycard so he can free Arnold before jumping off the rails onto his death.
Tammy and Snake go to Arnold's location and free him before his execution begins, Tammy asks him for the blueprints to the Metal Gear and runs off to hide them while Snake escorts a highly injured Arnold only to be interrupted by Brad. Snake pushes Arnold away and engages in a duel with Brad, only to start losing and almost die until Arnold interrupts the fight by throwing a grenade at Brad.
Arnold reveals that he got his memory back in the middle of his punishment and that there were actually two TX-11 cyberdroids that were dug up from Outer Heaven and that he was one of them, when they were being repaired their AI was also upgraded as well, so when Brad woke up he decided to steal the power from the second cyberdroid while he was still being upgraded. In the end Arnold was reprogrammed and was implanted fake memories of being kidnapped, however he became too smart and started trying to escape so he was sent to be thrown overboard to his death.
Arnold then throws himself at Brad and activates a self-destruct mode and tells Snake that after Brad's shield is blown up, he'll be able to use explosives to finally end him. In the end Snake wins thanks to Arnold's sacrifice and goes to find Tammy to read the blueprints but she insists that Snake should capture Bardo first before he escapes.
Snake finally finds where Bardo has been hiding and passes through security using Brad's keycard, but when Snake confronts Bardo he finds him tied up. Snake frees Bardo and asks him what happened to him and he says that his crew went insane and tried to take over the facility and use the mech he was fabricating to start a war and that they took his daughter hostage. Snake asks him about his daughter's name and he reveals that his daughter is actually Tammy, Snake reassures him that Tammy's alright and takes him out back to the warehouse area to reunite with Tammy.
Snake and Bardo run back and find that Tammy is not in the warehouse area, they start wondering what happened to her until hearing a commotion outside, when they go investigate they find the Metal Gear walking and attacking everyone on-sight, even those who helped make it. Snake and Bardo take cover behind some boxes and find out that the one who is piloting the Metal Gear and the mastermind behind the whole plan is actually Tammy.
Snake asks Tammy about why she would do something like this and she says that she grew up in the battlefield where most of her loved ones died, so when she saw her father "working with the enemy" for a "better future" she went mad and decided to take over the project and use the mech her father was working on as a weapon. Tammy then starts firing at Snake so he takes cover and escorts Bardo to a safe hiding spot until confronting Tammy as she pilots the "Metal Gear Typhoon".
Snake finally finds the Metal Gear's weakpoint and finally takes it down, letting it sink to the depths of the pacific ocean. However, when the Metal Gear falls everyone goes into a panic and runs away, leaving Snake confused until the reason they ran is revealed: The Metal Gear Typhoon was made to be the first Metal Gear model to acheive flight. However, Snake still manages to take the Metal Gear down and rescue an unconscious Tammy.
Snake starts calling helicopters to pick them up until the signal is disconnected when the Metal Gear starts blowing up and causing a chain reaction throughout the ship, Snake, Bardo and Tamy start escaping until finally reaching the helicopter. Bardo enters safely and Snake tries to enter while carrying Tammy until she wakes up and starts fighting back, refusing to live in a world where she has to live at peace with her family's killers, Snake tries to convince her to let go of the past but she doesn't listen, forcing Snake to go on one last duel until knocking out Tammy and dragging her back into the helicopter before it flies off and the facility starts falling down until sinking into the pacific ocean.
It then cuts to 2024, where we find out Snake has been trying to live a normal life after the events at the flying facility, Bardo has been elected as president of USA, Kyle escaped the flying facility when it started blowing up and joined Maverick Security Consulting Inc. and Tammy was arrested and even in prison she regrets her action and writes letters to Snake apologizing for her actions and wishing best of luck in his life.
Operation Machina (PS3/PS4-Only)
Operation Machina is a special extra mode where you play as Raiden, this mode is unlocked once you beat the main story mode.
It starts when Raiden sneaks into a facility building where a terrorist group is planning to upload a virus to the internet, after sneaking into the facility and tracking the leader of the organization, a man named "Ken", Raiden tries to get to him only to find he's already been spotted. Raiden fights through troops and gets to Ken only for him to escape into a bunker that requires a keycard, Raiden goes back and looks for a keycard only to find it's protected by a heavily armored soldier wielding a mace.
After getting the keycard and confronting Ken, he reveals that he already had uploaded the virus and that it was just starting to be downloaded into the main web, Raiden traps Ken and calls for him to be arrested while he runs to the Super Computer to delete the virus until it starts a defense mechanism by covering itself in an armored truck. Raiden eventually takes down the truck and deletes the virus before it can be spread.
This mode is much shorter compared to the main story mode but it features a new set of weapons, a new location and a new Codec team, which is actually the same Codec team from Metal Gear Rising with the new addition of Kyle.
Operation Angelus (Wii U-Only)
Operation Angelus is a special extra mode set in the Kid Icarus world where you can play as Pit, this mode is unlocked once you beat the main story mode and serves as a replacement for Operation Machina.
It starts when Pit is dropped off in a cavern that's been taken over by Underworld Forces led by "Orcos", Hades' apprentice who wants to avenge Hades by killing Pit and he wants to do this by forcing Dyntos to make a copy of the Great Sacred Treasure. Pit sneaks his way in and rescues Dyntos, however while taking him back out he's ambushed and Dyntos is taken away. Pit escapes and chases after Dyntos only to find who captured him: Cragalanche the Mighty, that's when Viridi reveals that she made a deal with Orcos to team up and take care of Skyworld, but after that Viriddi will take care of Orcos on her own.
After taking down Cragalanche and rescuing Dyntos he reveals that it's too late and that the Great Sacred Treasure copy is almost completed, so Pit runs back in and tries to destroy it only to be stopped by a magical gate that requires a key, Pit looks for the key and opens the gate only to see Orcos riding a complete Great Sacred Treasure copy. In the end, Pit takes down Orcos and the Great Sacred Treasure copy and he escapes as the cavern blows up.
This mode, just like Operation Machina, is way much shorter compared to the actual campaign but it features an all-new set of weapons and a new location. This mode also has a new Codec team based on Kid Icarus: Uprising consisting of Palutena, Dark Pit, Viridi and Magnus.