Metal Gear is the designation to various models of bipedal tanks. Metal Gear are behemoth machines capable of decimating lesser machines. Metal Gear have the distinction of being nuclear capable, firing warheads from their rail gun, eliminating the need for a missile, or launchpad allowing them to attack targets from anywhere in the world, on any kind of terrain. This peaked with Metal Gear REX which was sophisticated enough to launch a nuke from anywhere on earth and hit a target anywhere in the world, REX also had the distinction of being completely untraceable.

Generally speaking, the climax of a Metal Gear game is where the player must battle against the specific Metal Gear threat of that era.

Definition

The general definition of a Metal Gear prior to the collapse of the war economy is a mobile nuclear launch platform similar in purpose to ballistic missile submarines. However, its precise definition is debatable, as many other weapons have been designed to fill a similar role, or have used the same technology. The individual units have varied greatly in appearance and size, but their purpose has always been the same—to destabilize the global balance of power via the threat of covert long-range nuclear attack.

The term “Metal Gear” was coined by Soviet weapons scientist Aleksandr Leonovitch Granin to describe to Naked Snake in 1964 the “missing link” between infantry and artillery: infantry could roam the battlefield at will, but were both vulnerable and lacking in firepower; artillery could inflict immense damage upon an opponent while resisting similar damage, but was at the mercy of the terrain. Granin envisioned a tank with legs, enabling it to quickly traverse the battlefield, inflicting and repelling damage on a scale never before seen.

Following an encounter with a Gekko in 2014, Otacon explained to Solid Snake that what makes a “Metal Gear” is specifically its nuclear launch capability. Considering Granin’s original coinage of the term, it can be therefore assumed that a Metal Gear can be defined as a bipedal nuclear weapon. Not only does this negate the Gekkos and the Mk. II/Mk. III from being true Metal Gears, but it also discounts Metal Gear RAY. Otacon notes that RAY was an exception to the definition, as it was overall created under the premise of nuclear strategy (it targeting nuclear warhead-equipped Metal Gears).

After the end of the war economy era, the classification was redefined to simply mean any mech that exceeded the size of unmanned gear walkers such as Gekko. Furthermore, possessing nuclear weaponry was no longer required to being labelled as such due to the concept of deterrence being outdated by the rise in cyborg technology

Metal Gear RAXA (1970)

   
 Appears in: Metal Gear Solid: Portable Ops

The Intercontinental Ballistic Metal Gear (ICBMG) was developed for the Central Intelligence Agency by Nikolai Stepanovich Sokolov in the 1970s. Sokolov was heavily influenced by Granin’s designs when creating this Metal Gear. The idea for this version of Metal Gear was to use a large rocket to launch the actual Metal Gear unit itself into near-orbit before releasing it, allowing it to parachute back down to the target location where it would then launch its payload of nuclear weapons.

Metal Gear RAXA (pronounced “rasha”), was a prototype of the ICBMG created in 1970. Although considered to be the first Metal Gear, neither RAXA nor the ICBMG truly lived up to Granin’s original vision of a bipedal walking tank.

Metal Gear ZEKE (1974-1975)

   
 
Appears in: Metal Gear Solid: Peace Walker,Metal Gear Solid V: Ground Zeroes

Metal Gear ZEKE was the first fully bipedal tank. It was designed by the Militaires Sans Frontières (MSF) at the Mother Base by Huey Emmerich and Strangelove in 1974. It is equipped with a railgun, a radome, and a jetpack to increase mobility. Originally an unmanned weapon, Paz Ortega Andrade hijacked and modified it as manned weapon, and planned to launch a nuke at the United States’s Eastern Coast if Big Boss (Naked Snake) didn’t rejoin Cipher; however, it was heavily damaged in the ensuing fight. Strangelove noted afterward that it could at least regain the ability to walk, as she had made a backup copy of the AI, but whether it would be used again was up to Big Boss. During the Trojan Horse Operation in 1975 carried out by Skullface and XOF, they succeeded to destroy Mother Base along with ZEKE.

Metal Gear ST-84/Sahelanthropus (1984)

Appears in: Metal Gear Solid V: The Phantom Pain

In the 1980s, XOF stored and later deployed Metal Gear Sahelanthropus in Soviet territory. It had been developed by Huey Emmerich in 1981 after his capture by the Soviets. It featured a head similar to that of Metal Gear REX, although with only one eye on each side as opposed to REX’s three, a circular plate and legs similar to that of Metal Gear ZEKE. While normally taking on a hunched-over stance similar to REX, it also possessed the ability to stand completely upright and take on a disturbingly humanoid shape, being the only Metal Gear with fully functionally arms and hands. It was to be used as a marketing tool that would intimidate the world, forcing them to purchase nuclear weaponry from Skull Face, but its appearance was never made public. Unlike other Metal Gear, Sahelanthropus was piloted remotely by Skull Face and later Eli by using Tretij Rebenok’s psychokinetic powers as a conduit, a very unique method of control. It was stolen from XOF by Diamond Dogs after its defeat and eventually was completely destroyed after being hijacked by Eli. On the other hand, it takes its name from the first animals thought to stand up straight, “Sahelanthropus Tchadensis”, in the same vein that Metal Gear Sahelanthropus/ST-84 is the first Metal Gear to stand up straight.

Metal Gear TX-55 (1995)

   
 Appears in: Metal Gear

The Metal Gear TX-55 was the first globally documented bipedal tank designed (at force by Venom Snake as he wanted to battle against cipher/the patriots) at Outer Heaven by the Eastern scientist Drago Pettrovich Madnar in 1995. TX-55 proved Granin’s vision to be a potent weapon — a mobile nuclear launch system that made stationary missile silos obsolete. It was used to threaten and blackmail the rest of the world, but never launched any nukes. In fact, this Metal Gear was never actually deployed, as it was destroyed by Solid Snake before its development could be completed.

Metal Gear D (1999)

Appears in: Metal Gear 2: Solid Snake

Metal Gear D was a re-designed version of TX-55 (the TX-55 being a prototype for Metal Gear D) that was very similar in appearance. It was also developed by Dr. Madnar within Zanzibar Land in 1999. This Metal Gear also featured additional weapons for close quarters combat. Metal Gear D’s standard arsenal was comprised of a 60mm rotary cannon, a 5.56mm machinegun and a six-missile pod that could be armed with several different types of warhead. While its main purpose was to serve as a mobile launch platform for short-to-medium range nuclear warheads, it could also function as a weapon of conventional warfare.

It also carried a sensor system that consisted of the main camera, laser sights, an image sensor, and an infrared sensor. 

Metal Gear REX (2005;2014)

   
 Appears in: Metal Gear Solid 1: The Twin Snakes, Metal Gear Solid 4: Guns of the Patriots

Metal Gear REX was a Metal Gear developed for the United States Army. It was developed by Dr. Hal Emmerich, in a joint venture between ArmsTech and DARPA, at the nuclear weapons disposal facility on Shadow Moses Island in 2005. It was considered to be a revolutionary weapon – unlike all previous iterations of Metal Gear, not only could REX deliver a nuclear weapon both to and from any point on the globe, it was undetectable and untraceable. All previous Metal Gears were merely mobile ground-based launch systems for nuclear missiles, little more than the land-based equivalent of ballistic missile submarines. REX utilized a railgun, which fired much smaller projectiles without chemical propellants – factors which made them virtually invisible to radar. It thus completely negated the theory of Mutually Assured Destruction – whoever controlled it could launch a nuclear attack at any target at any time without fear of reprisal. Additionally, unlike all the previous Metal Gears, REX’s legs were heavily armoured rendering grenades useless.

Metal Gear RAY (2007-2009;2014-2018)

   
 Appears in: Metal Gear Solid 2: Sons Of Liberty, Metal Gear Solid 4: Guns of the patriots, Metal Gear Rising:Revengeance

Metal Gear RAY was a Metal Gear originally developed for the United States Marine Corps. It is, however, a Metal Gear by Granin’s initial definition – although RAY is a bipedal weapon, it lacks any form of nuclear armament. Nevertheless, it was originally created under the premise of nuclear strategy. In addition, it did serve as part of a true Metal Gear’s “conventional” armament – Arsenal Gear. RAY was designed and developed by the Pentagon and the Marines in 2007 as a countermeasure to the abundance of Metal Gear REX derivatives being developed due to REX’s plans being leaked onto the black market after 2005. For this reason, it was, until the creation of the Gekko, the only Metal Gear designed for close-range battle.

RAY is notable for being the first attempt at Metal Gear mass-production. The Patriots (via the U.S. Navy) produced twenty-five mass-produced Metal Gear RAY units to serve as guards for Arsenal Gear in 2009. They differed from the original RAY in that they were unmanned (the original intention of the Marine Corps), had no tail and were slightly smaller.

Metal Gear EXCELSUS (2018)

   
 Appears in: Metal Gear Rising:Revengeance 

When SOP and the Patriots fell following Liquid Ocelot’s Insurrection, PMCs acted on the development of cyborg technology as the information had been previously suppressed. The result was an abundance of cyborgs in the armies of PMCs. Due to the advantage of cyborgs capable of making decisions like other humans, the small unmanned gears such as the Gekko units were generating less favor in regards to urban combat. In response, AT Corp did a 180-degree turn and returned to develop a larger Unmanned Gear (UG) capable of overpowering cyborgs and tearing a path through urban terrain using its sheer size and power. The result was a new Metal Gear codenamed “Excelsus”. The vehicle was not armed with a nuclear weapon, instead being designed for the purpose of asymmetrical warfare in light of cyborg development. Although initially designed to be a UG, the final design required a pilot. Due to the term being redefined to mean a mech that far outclasses UG-walkers in size with nuclear deterrence becoming obsolete, it was also given the name “Metal Gear” despite lacking nuclear armaments.