In this game, Solid Snake abandons his retirement plans and isolation in Alaska to undertake a mission concerning the corpse of Big Boss. The story follows the infiltration mission that would later become known as "the Shadow Moses incident." Not only is the secret behind Solid Snake's birth revealed, but his brother also makes an appearance: Liquid Snake, who was born from the same genetic material. The story about genetics and illegal nuclear weapons was hailed by the media as the ultimate video game scenario of the 20th century, while the game received praise for its use of the Sony PlayStation's 3D graphics to provide an immersive infiltration experience. The game featured many new ideas, utilizing the controller's vibration function, as well as various secrets hidden in the game's packaging. This title was the third game released in the official Metal Gear series storyline.

This game depicts two different events: The new member of FOXHOUND, Raiden, takes on a group of terrorists who have seized an offshore facility in the Big Shell incident. This game, released on PlayStation 2, introduced players to the character of Raiden, who inherited many techniques and ideas from Solid Snake. In addition to the first-person aiming capability, players also had access to a variety of new actions, such as holding enemies and disposing of their bodies. It was characterized as "the best gameplay system of the 21st century." An ultimate version of the game called Substance was released later. This title was the fourth game released in the official history of the Metal Gear series.

The story narrates the beginning of the epic saga. It covers the events of both the Virtuous Mission and Operation Snake Eater, detailing how the man codenamed Naked Snake earned the title of Big Boss. While previous games in the Metal Gear series took place in more urban environments and involved infiltrating buildings, this game is set in a relentless jungle. In addition to hiding in the shadows, players can use outfits and face paint as camouflage to blend into their surroundings. This gameplay system was expanded in Metal Gear Solid 4: Guns of the Patriots. A version boasting the ultimate survival experience, named Subsistence, was released later. This title was the fifth game released in the official history of the Metal Gear series.

Solid Snake, a rookie in the FOXHOUND special forces unit, is sent on his first mission under the orders of his commander, Big Boss. His orders are to infiltrate the hostile nation of OUTER HEAVEN, where a bipedal tank capable of launching nuclear missiles from anywhere in the world is being developed. The story covers what would later be referred to as the Outer Heaven Uprising. The game's stealth-action gameplay, which saw players infiltrating enemy territories without being detected, and its hardboiled setting earned it critical acclaim worldwide. The game was recognized in the Guinness World Records as the first console game to use stealth as a core part of its gameplay. This groundbreaking title was the first game released in the official history of the Metal Gear series.

In this game, Solid Snake, who has left the FOXHOUND special forces unit, wants to settle the score with his nemesis, Big Boss. The story covers what later became known as the Zanzibar Land Disturbance, elevating the series' drama as it depicts the reason behind Big Boss's actions and how soldiers had lost their sense of purpose. While the previous game focused mainly on avoiding enemy detection, this new addition to the series introduced the concept of sound, where enemy soldiers could hear Snake's footsteps and players could knock on walls to attract enemy attention, allowing for even more thrilling stealth action gameplay. This title was the second game released in the official Metal Gear series history.