Metal Gear Solid

The series has long criticised the military industrial complex. Metal Gear Solid is cited with Cannon Fodder and Missile Command as a critical war game that came before Spec Ops: The Line, though not as a mainstream shooter.

Quietly tracking player actions lets the game surprise them later. Psycho Mantis reacts to how often you saved, how many traps you sprung and even what is on your PS1 memory card, calling you a very methodical man.

Explicit choices announce themselves, often with a notification, so their consequences rarely surprise. Quote: "the game can secretly and silently track your actions without you ever realising it."

An alert countdown lets players hide and reset the guards. A sighting puts guards into Alert; breaking line of sight moves them to Evasion with a visible countdown, and when it runs out they return to patrol. Players recover without reloading a save or killing everyone.

This state model is still the template in most stealth games. Metal Gear Solid V refines it: guards stop hunting fairly quickly, but the area stays on a cautious, heightened patrol for many in-game hours, so the reset doesn't break the fiction.

Enemies counter the player's favourite tactic once a threshold is passed. Metal Gear Solid V tracks headshots, unseen base takeovers and night infiltrations, then equips guards with helmets, traps or night-vision goggles.

It is not learning: the behaviours are scripted and simply switched on at thresholds. The effect is that no single tactic wins every time.

Camouflage lets Snake stand safely inside dangerous space. Metal Gear Solid 3's camouflage system changes the character instead of the space, letting Snake blend into surroundings, and Snake can interrogate enemies for patrol routes and ammo caches.

The Soliton radar told players exactly when they were safe. The radar shows enemy positions and vision cones, so players can see where a guard's sight cannot reach, and it jams when Snake is spotted. Tenchu's Ki Meter and Thief's Light Gem solve the same problem.

Drawing cones on a top-down radar is a workable way to show perception in 3D, but it makes players watch a small box in the corner. The Swindle puts the same information on the game world, and Sly Cooper uses torch light pools as a cleaner in-world cue.

Killing Ocelot ends the game because the past is fixed. Metal Gear Solid 3 gives a game over if you kill Ocelot, since he must live until 2005, showing how playable flashbacks restrict choice.

Missions start calm, and the player's goal is keeping them calm. Metal Gear Solid, released in October 1998 alongside Tenchu (August) and Thief (November), opens missions with guards patrolling and unaware of Snake's position or even his existence.

Each of the three games made staying unseen safer than fighting. Snake can crawl under objects, choke enemies out or hide in a box.

The Soliton radar told players exactly when they were safe. The radar shows enemy positions and vision cones, so players can see where a guard's sight cannot reach, and it jams when Snake is spotted. Tenchu's Ki Meter and Thief's Light Gem solve the same problem.

Drawing cones on a top-down radar is a workable way to show perception in 3D, but it makes players watch a small box in the corner. The Swindle puts the same information on the game world, and Sly Cooper uses torch light pools as a cleaner in-world cue.

Suspicious guards and wall knocking made small mistakes recoverable. Guards investigate odd sights and sounds before attacking, and players can exploit this by knocking on a wall to lure a guard one way while slipping past the other.

Tenchu uses poisoned food and Thief uses noisemaker arrows for the same kind of manipulation.

An alert countdown lets players hide and reset the guards. A sighting puts guards into Alert; breaking line of sight moves them to Evasion with a visible countdown, and when it runs out they return to patrol. Players recover without reloading a save or killing everyone.

This state model is still the template in most stealth games. Metal Gear Solid V refines it: guards stop hunting fairly quickly, but the area stays on a cautious, heightened patrol for many in-game hours, so the reset doesn't break the fiction.

Polygons brought Kojima back to the series. Kojima considered Metal Gear finished and wanted to make graphic adventures like Policenauts, until real-time polygons let him show a hiding player's view from inside a locker or under a table.

Quote: "if you are hiding under a table you can change the point of view."

Metal Gear 2 invented these rules, but Metal Gear Solid spread them. Metal Gear 2: Solid Snake already had a radar, loud metal grates, suspicious guards, wall knocking and a reset to neutral, but it ran only on the MSX2 in Japan and barely influenced anyone.

The 1998 game's success did: Splinter Cell was built to rival Metal Gear Solid 2, and Volume is directly influenced by Metal Gear Solid. Like Doom with the shooter, the popularising game is just the first one to be really successful.

Stylised subtitles and unsubtitled barks shut out deaf players. Metal Gear Solid V uses a scribbly, hard to read subtitle font, and the enemy shout of 'Grenada!' carries critical danger information through sound alone.

Call of Duty pairs its grenade bark with a clear visual cue. Quote: "This is not the time to keep up your brand identity, this is the time for clarity."

Score rewards stealth without punishing players who go loud. Missions add points for accuracy, speed and rescues and deduct them for being spotted or hit, so careful play ranks higher while gung-ho play is still allowed.

Quote: "you're not exactly punished for playing in a gung-ho, Rambo-kinda way - but you are rewarded for being more sneaky and Snake-like."

A too-reliable tranquilliser gun crowded out creative plans. Mark Brown finished many missions by abusing the silenced tranquilliser gun, because a dependable option beats risky inventive ones.

Hitman makes Agent 47 weak in firefights and Zelda breaks weapons to push players away from the easy answer.

Enemies counter the player's favourite tactic once a threshold is passed. Metal Gear Solid V tracks headshots, unseen base takeovers and night infiltrations, then equips guards with helmets, traps or night-vision goggles.

It is not learning: the behaviours are scripted and simply switched on at thresholds. The effect is that no single tactic wins every time.

S ranks add a mastery goal on top of easy completion. Players can be sloppy and call in a helicopter to finish, but an S rank demands better play, so each player chooses how hard to push.