The story of Metal Gear Solid follows Solid Snake, a retired soldier who infiltrates a nuclear weapons disposal facility to neutralize the terrorist threat from FOXHOUND, a renegade special forces unit. Snake must liberate two hostages, the head of DARPA and the president of a major arms manufacturer, confront the terrorists, and stop them from launching a nuclear strike.

Metal Gear Solid was well-received, shipping more than six million copies, and scoring an average of 94 out of 100 on the aggregate website Metacritic. The commercial success of the title prompted the release of an expanded version for the PlayStation and PC, titled Metal Gear Solid: Integral; and a remake, Metal Gear Solid: The Twin Snakes was later released for the Nintendo GameCube. The game has also spawned numerous sequels, prequels, a port of the game to Windows PCs and spin-offs, including several games, a radio drama, comics, and a novel.

Gameplay

Despite a transition to 3D, Metal Gear Solid's gameplay remains similar to its 2D MSX2 predecessor Metal Gear 2: Solid Snake. The player must navigate the protagonist, Solid Snake, through the game's areas without being detected by enemies. Detection is triggered by the player moving into an enemy's field of vision and sets off an alarm that draws armed enemies to his location. This also triggers "alert mode" and the player must then hide and remain undetected, at which point “evasion mode” begins and once the counter reaches zero the game returns to "infiltration mode" where enemies are not suspicious of Snake's presence. The radar cannot be used in alert or evasion mode.

To remain undetected, the player can perform techniques which make use of Solid Snake's abilities and the environment, such as crawling under objects, using boxes as cover, ducking or hiding around walls, and making noise to distract enemies. These are carried out using the third-person camera; which often changes its angle to give the player the best view of the area possible, and an on-screen radar, which displays enemies and their field of vision. Snake can also make use of many items and gadgets, such as infra-red goggles or a cardboard box disguise. The emphasis on stealth promotes a less violent form of gameplay, as fights against large groups of enemies will often result in serious damage for the player.

Intermixed with the player's progress are cut scenes and codec conversations as well as encounters with bosses. To progress, players must discover the weaknesses of each boss to defeat them. Game controls and play strategies can also be accessed via the Codec radio, where advice is delivered from Snake's support team; for example, the support team may chastise Snake for not saving his progress often enough, or explain his combat moves in terms of which buttons to press on the gamepad. The Codec is also used to provide exposition on the game's backstory. Completion of the title provides the player with a statistical summary of their performance, and a "code name" based upon it, typically the name of a common animal.