Outer Heaven Uprising

200 kilometers north of the region of Galzburg, South Africa, laid the fortress of Outer Heaven, a heavily fortified state that had been founded by a legendary mercenary in the late 1980s.

Operation Intrude N312

In 1995, the western world had received intelligence that warned of a weapon of mass destruction that was supposedly being constructed deep within the fortress of Outer Heaven. The government called in the high-tech Special Forces unit FOXHOUND, commanded by the legendary soldier Big Boss, to infiltrate the fortress, and ordered them to send in an agent to assess the situation and neutralize whatever threat the weapon posed to the western world. The mission was carried out by Gray Fox, one of FOXHOUND's top agents. His objective was simply to analyze the threat Outer Heaven posed and to neutralize it. However, the mission ended in failure as Gray Fox was captured. His final transmission before his disappearance simply read: "Metal Gear..."

Operation Intrude N313

Rookie FOXHOUND operative Solid Snake, was ordered by Big Boss to perform a follow up mission entitled Operation Intrude N313. His mission objectives were to rescue the missing agent Gray Fox, and to find out the truth behind Metal Gear.

Snake infiltrated Outer Heaven via an underwater insertion, and proceeded into the base, eventually managing to locate Fox with intel provided by Outer Heaven's prisoners and resistance leader Kyle Schneider. To get there, Snake allowed himself to be captured, and then after being thrown into a prison, he managed to break through a weakened wall to get to Fox's cell next door. Gray Fox then revealed to Snake the true meaning behind Metal Gear: a walking battle tank capable of launching a nuclear missile from any kind of terrain. Luckily it was still in a hangar within the fortress and had not yet been activated. Fox told Snake to find Dr. Drago Pettrovich Madnar, the creator of Metal Gear and the only person who knew how to destroy it.

Mercenary

After fighting his way through Outer Heaven mercenaries Shotmaker and Machinegun Kid, Snake traversed the rooftop of Building 1 in order to reach the inner courtyard via parachute, also donning a Bomb Blast suit to bypass the wind barrier. Before he could reach the veranda, however, he had to fight off a Hind D gunship stationed in his path. After destroying it with a grenade launcher, Snake parachuted down into the courtyard, arriving at Madnar's cell, only to find it empty. However, he saved another hostage who revealed to him that Madnar was still alive, but that he had been relocated to the basement of the Building 2. While crossing the interconnecting desert between the two buildings, Snake was forced to battle a tank that had been recently deployed, using land mines to destroy it. Afterwards, Snake disguised himself as an enemy officer in order to sneak into the Building 2. Proceeding to the basement, he eventually found "Dr. Madnar", who immediately revealed himself to be a decoy and activated a suicide trap. Snake quickly avoided the trap and, confused, continued his search for the real Dr. Madnar, encountering and defeating Fire Trooper on the way.

Snake came into contact with Jennifer, another resistance member, who helped him locate the real Dr. Madnar and provided him with a rocket launcher, which he could use to defeat the seemingly invincible Bloody Brad cyberoids, who were guarding the area near to where Madnar was being held.

After destroying Bloody Brad, Snake entered Madnar's cell. However, Madnar would only tell Snake how to destroy Metal Gear if he rescued his daughter, Ellen, who had also been imprisoned. Snake made his way back to the basement of Building 2 where he was contacted by resistance member Diane, who advised him on how to locate Ellen. She was in the basement of Building 1, but luckily the two basements were connected by an underground passageway, though it was filled with pit traps, which Snake had to avoid. Eventually rescuing Ellen, she told Snake that her father had been forced to develop Metal Gear against his will.

Metal Gear TX-55

After Snake retraced his steps, Dr. Madnar informed him that Metal Gear TX-55 was located on the 100th floor basement of Building 3, located 20 km to the north. In order to destroy it, Snake needed to place Plastic Explosives on its feet in a specific order. Determined to destroy Metal Gear, Snake headed to Building 3. Once there, he was ambushed by enemy forces, but managed to slip by and made his way to the elevator. However, as he drew closer to the underground base, Big Boss started to act strangely, providing faulty information that would have delayed Snake's progress, and eventually telling him to abort the mission.

Reaching the 100th floor basement, Snake found he didn't have the right card key to continue further. Contacted again by Jennifer, she informed Snake of a wall he could destroy in order to locate an oxygen tank that he could use to swim through the drainage duct in Building 2 in order to find the required card key. Jennifer also told Snake to save her brother, and threatened not to help him anymore if her brother was harmed.

After making his way through the drainage duct, Snake was challenged by Dirty Duck who was holding the card key Snake needed. Duck hid himself behind hostages and used boomerangs to attack Snake. Snake awaited his chance to attack and took it, defeating Duck at close range. Rescuing the hostages, one of them revealed himself to be Jennifer's brother, who thanked Snake and gave him information to aid in his escape from the fortress.

Return of FOXHOUNDER

Heading back to the 100th floor basement of Building 3, Snake was contacted by Schneider regarding the truth behind Outer Heaven's leader, but his transmission was cut off before he was able to finish.

Snake pressed on and found himself in Metal Gear's hangar. Placing explosives on its feet as per Madnar's instructions, while avoiding gun cameras, it wasn't long before Metal Gear was destroyed. Suddenly, Outer Heaven's self-destruct sequence was activated. Making his escape, Snake came face-to-face with the legendary mercenary of Outer Heaven, which turned out to be none other than Big Boss himself.

Big Boss informed Snake that he had only been sent in to gather false information. However, because Snake had achieved too much, Big Boss told him that he had crushed his ambitions and would not die alone. After a ruthless battle, Snake defeated Big Boss and quickly made his way for the escape route, with the timer for the self-destruct sequence ticking away.

After successfully escaping, and with Outer Heaven exploding behind him, Solid Snake called back to HQ, informing them that Metal Gear had been destroyed, and that Operation Intrude N313 had been a success. It was later revealed that Big Boss survived the destruction of Outer Heaven and vowed that he and Snake would meet again...