[3] Players control Solid Snake, an operative of the special forces unit FOXHOUND, who goes on a solo infiltration mission into the fortified state of Outer Heaven to destroy Metal Gear, a bipedal walking tank capable of launching nuclear missiles from anywhere in the world, as well as rescue a number of fellow agents who have been captured by the enemy.

The player controls a military operative codenamed Solid Snake, whose objective is to infiltrate the enemy's base while avoiding visual contact and direct confrontation with patrolling guards.

The method of escaping varies depending on the circumstances behind discovery: Snake starts his mission unarmed, but can arm himself with numerous firearms and explosives that can be obtained throughout the enemy's stronghold.

A transceiver is available for Snake to keep in touch with his commanding officer, Big Boss, or one of the resistance members operating covertly near Outer Heaven (Schneider, Diane, and Jennifer).

Each of Snake's allies specializes in a specific subject and will usually provide information or advice based on the player's current area, although a reply is not always guaranteed.

The MSX2 version requires the use of a tape drive (such as the Sony Bitcorder) in order to save and load game progress from checkpoints.

Versions on later platforms eliminated these complicated requirements thanks to standardized storage devices such as memory cards and internal disk drives.

He is assisted via radio by his commanding officer Big Boss (later retconned to be a body double, the Big Boss's phantom), who offers information about mission objectives and items; as well as a local Resistance movement composed of leader Schneider, a former architect who guides Snake through the layout of the fortress and knows the locations of key items; Diane, a former positive punk vocalist who provides information on the enemy forces from her home; and Jennifer, who infiltrated Outer Heaven's medical staff to find her missing brother and assists Snake as an inside agent.

Among the prisoners Snake rescues are Grey Fox (Gray Fox in the later versions), a FOXHOUND agent who was captured during a previous mission; Dr. Pettrovich (Dr. Drago Pettrovich Madnar in later releases), a robotic engineer who is working for Outer Heaven against his will; and the doctor's daughter, Elen, who was kidnapped by the enemy to coerce her father into developing Metal Gear.

The bosses include Shoot Gunner (renamed Shotmaker in later versions), a former Spetsnaz agent specializing in the riot gun; Machinegun Kid, a former SAS operative armed with a machine gun; Fire Trooper, a former GSG 9 operative who uses a flamethrower; Coward Duck (Dirty Duck in later releases), a boomerang throwing terrorist who shields himself with hostages; Arnold (Bloody Brad in later releases), two TX-11 class androids designed by Dr. Pettrovich; and the legendary mercenary who founded Outer Heaven, whose true identity is unknown until the end.

Near the end of the 20th century, the West discovers that a weapon of mass destruction is being constructed inside Outer Heaven, a fortified state founded by a "legendary mercenary" 200 km north of Galzburg, South Africa.

The special forces unit FOXHOUND sends top agent Gray Fox to infiltrate the fortress, assess the situation and neutralize the threat.

Fox explains that Metal Gear is the codename of a nuclear-equipped bipedal walking tank, which can engage in all forms of combat and launch nuclear weapons from any location.

Big Boss begins to act strangely, giving misleading advice that leads Snake into several traps, and eventually ordering him to abort the mission (breaking the fourth wall by telling the player to turn off the system).

The corrupt leader reveals that he had been using his connections to steal military intelligence, establish his own mercenary force, and fund his activities.

Having lost Metal Gear and much of his force, Big Boss starts the self-destruct sequence for the compound, and promises he will not die alone; Snake will join him.

[12] The packaging illustration used for the retail releases of the game, which depicts the protagonist Solid Snake holding a gun, was traced over a publicity still of Michael Biehn posing as his character Kyle Reese from the 1984 film The Terminator.

This was followed by an English localization for the Nintendo Entertainment System (or NES) released in North America in June 1988 (published by Konami's Ultra Games division) and in Europe and Australia sometime in 1989.

[23] According to Kojima, the port was developed by another Konami division at Tokyo which was given the source code from the MSX2 version without the consent of the original team.

Due to hardware limitations with the mapper used, the Metal Gear boss ended up being replaced by a Supercomputer guarded by four enemy soldiers.

[28] In addition to the removal of the Metal Gear tank, the Hind D boss on the rooftop of Building 1 was replaced by a pair of armed turret gunners called "Twin Shot".

When Snake is killed by the enemy or loses his life by certain other means, the player is given a choice to continue the game from the last checkpoint or quit and resume later with the given passcode.

The passcode keeps track of Snake's rank (which determines his checkpoint in this version), inventory, hostages rescued, bosses defeated and certain event flags.

[33] An emulated port of the Famicom version was also included in a bonus disc packaged alongside Metal Gear Solid: The Twin Snakes in a limited edition GameCube console bundle released in Japan.

They concluded positively on the quality of the game, saying that if "this standard of Konami software is maintained then maybe more people will think hard about joining the other 200,000 MSX owners".

[21] Computer Gaming World also reviewed the NES version, praising its "strong concept" but stating it was "something less than a total success".

"Theme of Tara" is one of the tunes that can be heard in the "Shadow Moses Island" stage in Super Smash Bros. Brawl for the Wii, the music for the beginning section of the Battleship Halberd Interior stage of the Adventure mode, where Snake officially enters the storyline, and can also be selected as music with an iPod item in Metal Gear Solid 4: Guns of the Patriots.

The gamebook is set two years after the events of the game, in which Solid Snake is called back into action after FOXHOUND receives intelligence on a terrorist group who have obtained the plans for Metal Gear and are now mass-producing the mech.

[54] This book adheres much more closely to the localized version of the backstory as presented in the North American packaging and manual, as opposed to the actual in-game plot which was not changed to reflect this difference.

A Metal Gear remake mod for Alien Swarm was in development that was granted permission by Konami to use copyrighted material with the agreement that they don't make a profit from the recreation or accept donations for the production.