Fourth wall

The fourth wall is a term used to describe the imaginary wall between the audience and the stage, or in this case the gamer and the video game. The term derives from a movie or television set having three walls; the fourth wall is the camera. In effect, it is the separation of the real and the imagined. The origin of the term the fourth wall was first used in theater, where actors would acknowledge the presence of the audience through actions or speech. In the video game world, the fourth wall is often addressed in a humorous manner. In the early days of gaming, such things as putting certain information not available in-game in instruction manuals or on box-art were rudimentary forms of software piracy prevention.

Origin
The term "fourth wall" stems from the absence of a fourth wall on a three-walled set where the audience is viewing the production. The audience is supposed to assume there is a "fourth wall" present, even though it physically is not there. This is widely noticeable on various television programs, such as situational comedies, but the term originated in theatre, where conventional three-walled stage sets provide a more obvious "fourth wall".

The meaning of the term "fourth wall" has been adapted to refer to the boundary between the fiction and the audience. "Fourth wall" is part of the suspension of disbelief between a fictional work and an audience. The audience will usually passively accept the presence of the fourth wall without giving it any direct thought, allowing them to enjoy the fiction as if they were observing real events. It is the invisible barrier between realities.

The presence of a fourth wall is one of the best established conventions of fiction and as such has led some artists to draw direct attention to it for dramatic effect. This is known as "breaking the fourth wall."

Fourth Wall References in the Metal Gear Saga
The Metal Gear series is notorious for breaking the fourth wall, sometimes many times in a single game. In fact, one could argue that Metal Gear is the most famous fourth wall breaking game, given the popularity and infamy of the Psycho Mantis boss battle from Metal Gear Solid.

Common Elements

 * Snake's support team will describe actions using terminology such as "circle," "square," and "Action Button," referring to the Playstation 2 Dual Shock Controller.
 * Gaming magazines and gravure idol posters also appear in all of the Solid series games.

Metal Gear 2: Solid Snake

 * The player must use a tap code found in the game's instruction manual to decipher codec frequencies

Metal Gear Solid

 * The player must find Meryl's frequency using a screenshot on the back of the package
 * Master Miller warns the player to use the bathroom frequently as to not miss one of the game's cutscenes, and to not play while tired
 * During the battle with Psycho Mantis:
 * Psycho Mantis reads the player's Playstaion memory card. If you have corresponding Konami-based savefiles, Psycho Mantis will comment on them. (eg. "I see you like Castlevania!") Mantis also does this in Twin Snakes, although with Nintendo saves instead.
 * Psycho Mantis tells the player he will move his controller using his mind, and to place it on the ground. The camera turns to Snake, who nods approvingly, as to say "go ahead, it's safe."
 * Using his blackout technique, Psycho Mantis will change the player's screen to a black screen reading "HIDEO" in the top corner, as to replicate most standard television set's VIDEO setting.
 * The player must physically change the controller's port on the Playstation or Gamecube, to prevent Psycho Mantis from "reading their mind."
 * When being tortured by Revolver Ocelot, he remarks that if the player uses a turbo controller on that part of the game, he'll know and automatically kill Snake. He also mentions that there "are no Continues, my friend." Obviously, this is the only part of the game where if Snake dies, you can't continue.

Metal Gear Solid 2: Sons of Liberty

 * The player can press the shoulder buttons on the Dual Shock controller to hear what either Snake or Raiden are "thinking" during codec conversations.
 * The entire Arsenal Gear sequence, after the virus is implanted onto GW, is a fourth wall break. Colonel Campbell and Rosemary make cryptic messages, urging the player to turn off the console, saying lines from previous games - Metal Gear and Ghost Babel, and famously spouting gibberish. Also, at one point, the radar screen shows a gravure idol instead of the typical radar screen.
 * Snake, after meeting Raiden in the Arsenel Gear's bowels, remarks that he has "infinite ammo." This is a nod to Metal Gear Solid's infinite ammo bandana item that is acquired in the Meryl ending.