Action games are no strangers to outlandish tech, with Metal Gear being at the forefront. Metal Gear's titular bipedal nuke-launching mechs are less effective than ordinary launch silos. AI is more of a threat to the creative community than the US political system, and if it was, it would likely try to control the internet from ordinary, boring server rooms than from a giant underwater fortress like in Metal Gear Solid 2.
However, the Metal Gear Solid series combines fantasy stuff with genuine military hardware. SOCOM pistols, Stinger missiles, M1 Abrams Tanks, Hind-Ds, Harrier jump jets, and more have all appeared in the series in one form or another. Then there are these bizarre pieces of technology that, despite seeming like something Hideo Kojima cooked up in a developer meeting, are real.
10 Flying Platforms
In Metal Gear Solid 3, as Naked Snake is about to move upriver, he’ll see Russian soldiers move into positions in these weird, hovering platforms that look like something that would have 007's very own James Bond confused. Some fans even felt it took them out of the game as they looked too hokey, even next to the guy who could control bees. However, vertical take-off & landing (VTOL) platforms have been a thing since 1954.
That said, the ones used in the game resemble the newer, nimbler, and armored Williams X-Jets from the 1980s than the bulky, more exposed VZ-1 Pawnee of the 1950s. They’re also both American designs, showing that the Philosopher's Legacy made Colonel Volgin's pockets very deep.
9 Fulton Recovery System
One of the more entertaining things to do in Peace Walker and Metal Gear Solid 5 was to abduct guards by strapping Fulton balloons onto them. It was hilarious and ruthless. It was a good way to build up Mother Base’s staff, unlock extra tech capabilities, and more. However, they first debuted in MGS3, where their depiction was much closer to its real-life equivalent.
The real deal didn't lift people or objects up with the power of helium alone. Instead, they held up a long, nylon cable that a plane would fly by and catch with its special "sky anchor", which would then winch them up. The soldier had to fill the balloon up himself with helium tanks, then catch the plane's attention with a flashlight. So, Snake's more involved, fiddlier process at the end of the Virtuous Mission is more authentic than the sudden kidnaps in later games.
8 Shagohod
The Soviet OKBs did consider some fantastical designs, like a VTOL surface-to-air missile-launching platform. But a giant tank that could extend an intermediate-range missile’s reach with a run on an airport-style runway was never on the cards. However, the name of the Shagohod and parts of its design were inspired by Soviet tech.
The front half is based on the Shnekohod (“auger”), a vehicle that used counter-rotating screws to move instead of wheels. The Soviets used them to recover Soyuz spacecraft and crew during the 1970s since they could move more easily through mud, snow, and water than typical trucks. Granin may have favored legs for marginal terrain travel in MGS3, but these screws worked out better in real history.
7 Laryngophones
If MGS5 players took Venom Snake out into the field shirtless, they’d see him with a bowtie-looking object on his throat. As strange as it looks, it’s a real piece of tech called a laryngophone, or throat microphone, and they’ve been used on the field for over a century.
First designed for the front in World War 1, the throat microphone would pick up what the person was saying by close contact with their throat, turning the vibrations and tracheal pressure into sounds. That way, they wouldn’t be drowned out by strong winds or other loud noises. Outside war, they’re used by the emergency services and motorcycle racers.
6 Nanomachines
Originally mentioned in Snatcher, Kojima brought nanomachines into Metal Gear Solid 1 as the reason Snake could withstand the Alaskan winter and communicate via Codec. Then Metal Gear Solid 4 turned them into the cause of (and solution to) all of its problems. Then Metal Gear Rising made them the source of Senator Armstrong's power. Why? Nanomachines, son.
They got out of hand, as nanotechnology is currently in its infancy. That said, their depiction in MGS1 is quite close to how nanomachines are used. They can administer drugs and treat biological tissue, which is how Naomi Hunter uses them to fix Snake up after his first torture session in the game.
5 Cypher
While the tech here has been real, Metal Gear has embellished them for dramatic effect. Nanomachines won’t run amok and turn all life into gray goo like then-Prince Charles of Great Britain feared in 2003. But MGS2 managed to faithfully reproduce a genuine piece of the military without any fanciful additions.
The Sikorsky Cyphers were UAV drones that used two enclosed rotors to take off and land. They could be used as mobile security cameras as they were in MGS2. However, they were also intended to carry loads up to 50 lbs, relay radio signals, and detect chemicals. They couldn't fire guns, so that's a Metal Gear-exclusive feature.
4 Stealth Camouflage
The power to turn invisible has tantalized humanity since the tale of Perseus in Greek mythology. But since Metal Gear is more about cutting-edge technology, they turned it into a device that the player has to unlock. They do make things much easier, but they're more often used as a way for the player to smack the guards around without any trouble.
There have been theoretical and experimental applications of “active camouflage/optic camouflage” technology in real life. They're just not advanced enough to match the game's depiction. Susumu Taichi’s Invisibility Cloak could refract light around its wearer, except they could still be seen at other angles. Phased-array optics could potentially make it work at all angles, but it only remains as potential for now.
3 Railguns
Regular firearms essentially use controlled explosions to send their bullets flying. Railguns use electromagnetic force to launch their projectiles instead. It makes for a cleaner, more powerful shot, and their use in Metal Gear has shown them to be a force to be reckoned with. REX's railgun is perhaps the most famous as it was meant to fire an undetectable nuke. It would make for a sad moment to see someone hit by this devestating weapon of war.
While that might be far-fetched, Otacon's initial thought of using it to shoot down enemy missiles is more on the money. That's how the US Navy and other military branches are planning on using them. But they're more likely to be installed on ships than made into handheld weapons like in MGS2, MGS4, and Peace Walker because they require a very long barrel to work. Though that could change in the next decade or so.
2 High-Frequency Blades
The Japanese katana has held a mystique that other blades have lacked thanks to their seriously sharp edge, and appearances in movies, TV shows, and video games. Grey Fox, Mr. X, and Raiden all swung specialized ones called High-Frequency Blades that use vibrations to make them slice through metal more easily, which is real tech, somewhat.
While they haven’t been used for katanas, oscillating/vibro blades have been used in DIY and cooking to cut through materials like wood, thinner metals, and crusty bread more easily. Though if they were used on thicker stuff with enough heft, it would possibly leave white-hot cuts like Raiden's blade does in MGR.
1 Arsenal Ship
Arsenal Gear could never be real. Solidus Snake himself says in MGS2 that it’s a conspicuous target without a horde of equally improbable military tech like the RAYs guarding it. However, the game’s lore points out that the US Navy only got to get started on it after the failure of an earlier project called “Arsenal Ship”, which was real and proposed by the Navy in 1996.
It would’ve been a floating cruise missile platform controlled either from a nearby cruiser or an aircraft. It reached the concept stage, but it lost its funding back in 1998. The private sector has considered bringing it back, as has China and South Korea, with the latter planning to make 3 of them by the end of the 2020s.