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A stealth game (sometimes known as a sneak 'em up) is a type of video game in which the player primarily uses stealth to avoid or overcome antagonists. Games in the genre typically allow the player to remain undetected by hiding, sneaking, or using disguises. Some games allow the player to choose between a stealthy approach or directly attacking antagonists, but rewarding the player for greater use of stealth. The genre has employed espionage, counter-terrorism, and rogue themes, with protagonists who are special forces operatives, spies, thieves, ninjas, or assassins. Some games have also combined stealth elements with other genres, such as first-person shooters and platformers.
Elements of "stealth" gameplay, by way of avoiding confrontation with enemies, can be attributed to a diverse range of games, including Pac Man (1980). Early maze games have been credited with spawning the genre, including Manbiki Shounen (1979), Lupin III (1980), Castle Wolfenstein (1981), 005 (1981) and Metal Gear (1987). The genre became a mainstream success in 1998, with Tenchu: Stealth Assassins, Metal Gear Solid and Thief: The Dark Project all being released in that year. These games were followed by other successful stealth series, such as Hitman and Splinter Cell.
Unlike most action games, stealth games challenge the player to avoid alerting enemies altogether. The core gameplay elements of the modern stealth game are to avoid combat, minimize making noise, and strike enemies from the shadows and behind. Completing objectives without being detected by any enemy, sometimes referred to as "ghosting" is a common approach to stealth games. Avoiding detection may be the only way to successfully complete a game, but there are usually multiple ways to achieve a goal with different pathways or styles of play. Players can hide behind objects or in shadows, and can strike or run past an enemy when the enemy is facing the other way. If the player attracts the attention of enemies, they may be able to hide and wait until the enemies abandon their search. Thus, planning becomes important, as does trial-and-error. Some stealth games put more emphasis on physical combat skill when the player is spotted. Some games offer a choice between killing or merely knocking out an enemy. When ghosting is optional, or not well-supported by a game, players may still attempt to avoid combat for moral reasons or as a demonstration of skill. Early on in the development of the stealth genre these games were referred to as sneak 'em up games.
When hiding in the dark is a gameplay element, light and shadow become important parts of the level design. Usually the player is able to disable certain light sources. Stealth games also emphasize the audio design when players must be able to hear the subtle sound effects that may alert enemies to their actions; noise will often vary as the player walks on different surfaces such as wood or metal. Players who move recklessly will make more noise and attract more attention.
In order for a game to include stealth gameplay, the knowledge of the artificial intelligence (AI) must be restricted to make it ignorant to parts of the game world. The AI in stealth games takes into specific consideration the enemies' reactions to the effects of the player's actions, such as turning off the lights, as opposed to merely reacting to the player directly. Enemies typically have a line of sight which the player can avoid by hiding behind objects, staying in the shadows or moving while the enemy is facing another direction. Enemies can also typically detect when the player touches them or moves within a small, fixed distance. Overall, stealth games vary in what player actions the AI will perceive and react to, with more recent games offering a wider range of enemy reactions. Often, the AI's movements are predictable and regular, allowing the player to devise a strategy to overcome his adversaries. Players are often given limited methods of engaging opponents directly in stealth games, either by restricting the player to ineffective or non-lethal weapons, equipping adversaries with far superior equipment and numbers, or providing the player with a limited amount of health that makes most combat scenarios extremely dangerous. Stealth games sometimes overlap with the survival horror genre, in which players are forced to hide from and evade supernatural or occasionally mundane enemies as they attempt to track down the player. Examples of hybrid stealth/horror games include Amnesia: The Dark Descent, Outlast, and the Penumbra video game series.
Early developments: 1979–1997
According to Retro Gamer's John Szczepaniak, the first stealth game was Manbiki Shounen (Shoplifting Boy), published in November 1979. The PET 2001 personal computer game was developed by Hiroshi Suzuki and involves a boy entering a convenience store and attempting to shoplift by stealing "$" symbols while avoiding the line-of-sight detection of the owner. If caught, the player is led away by the police. Suzuki presented the game to developer Taito, which used it as inspiration for their similar stealth arcade game, Lupin III (based on the manga and anime of the same name), released in April 1980. In November 1980, Suzuki developed a sequel, Manbiki Shoujo (Shoplifting Girl).
Castle Wolfenstein, originally available in 1981, employed stealth elements as a focus of the gameplay. Players were charged with traversing the levels of Castle Wolfenstein, stealing secret plans and escaping. Players could acquire uniforms to disguise themselves and walk by guards undetected. Beyond Castle Wolfenstein, released in 1984, included some additions to its predecessor, such as a dagger for close-range kills and a greater emphasis on disguising in enemy uniform. id Software's updated 1992 remake Wolfenstein 3D was originally going to feature some of the original's stealth gameplay, such as body hiding, but this was cut to make the game faster paced. As a result of these changes, Wolfenstein would instead pave the way for later 3D action games, specifically first-person shooters.
In 1981, Sega released an arcade game called 005 in which the player's mission is to take a briefcase of secret documents to a waiting helicopter while avoiding enemy flashlights and use boxes as hiding spots. 005 holds the Guinness World Record for being the first stealth game.
In 1985, Durell Software released Saboteur, a game in which the player controls a ninja who has to infiltrate a facility and find a disk while avoiding or defeating security cameras, guards, and dogs. Retro Gamer has called this "the original stealth game". Mindscape's Infiltrator, released in 1986, combined a flight simulator with a stealth-based "ground mission". In this ground mission, the protagonist attempts to sneak into enemy territory using false IDs to avoid detection and knock-out gas to incapacitate enemies. The goal of this mission is to photograph secret documents while avoiding alarms.
Hideo Kojima's Metal Gear, released in 1987 for the MSX2 and the Nintendo Entertainment System in 1988, utilized stealth elements within an action-adventure framework, and was the first mainstream stealth game to be released on consoles. Since the MSX2 was not available in North America, only the NES version was released there. Metal Gear placed a greater emphasis on stealth than other games of its time, with the player character Solid Snake beginning without any weapons (requiring him to avoid confrontation until weapons are found) and having limited ammunition for each weapon. Enemies are able to see Snake from a distance (using a line-of-sight mechanic) and hear gunshots from non-silenced weapons; security cameras and sensors are placed at various locations, and a security alarm sounds whenever Snake is spotted and causes all enemies on screen to chase him. Snake could also disguise himself in enemy uniform or a cardboard box, and use his fists to fight enemies.
The sequel Metal Gear 2: Solid Snake was released in 1990 for the MSX2. It further evolved the stealth gameplay of its predecessor and introduced most of the gameplay elements present in Metal Gear Solid, including the three-dimensional element of height, allowing players to crouch and crawl into hiding spots and air ducts and underneath desks. The player could also distract guards by knocking on surfaces and use a radar to plan ahead. The enemies had improved AI, including a 45-degree field of vision, turning their heads left and right to see diagonally, the detection of various different noises, being able to move from screen to screen (they were limited to a single screen in earlier games), and a three-phase security alarm (where reinforcements are called in to chase the intruder, then remain on the lookout for some time after losing sight of the intruder, and then leave the area). The game also had a complex storyline and improved graphics.
Establishing a genre: 1998–2002
Although stealth gameplay had appeared in previous games, 1998 is seen as a turning point in gaming history because of the release of Tenchu: Stealth Assassins, Metal Gear Solid, and Thief: The Dark Project. The ninja-themed Tenchu: Stealth Assassins was the first 3D stealth based-game. Months later, the highly anticipated Metal Gear Solid transformed its modestly successful franchise into a mainstream success. The increased power of the PlayStation console over previous platforms allowed for greater immersion in terms of both story and game environment. Metal Gear Solid has been credited with popularizing the stealth genre. Thief: The Dark Project is also credited as a pioneer of the genre. It was the first stealth game using the first-person perspective, dubbed a "first-person sneaker", or "sneak-em-up", and the first to use darkness and shadows as the mode of concealment. Another of Thief's most noteworthy contributions to the genre was the use of sound as a central mechanic. The robust simulation of sound meant players had to be mindful of the sounds they made, including what kind of surface they were traversing, lest they draw attention to them. Conversely, it meant guards could be heard from a distance and the surfaces they moved on could be identified based on the sounds they made.
With further releases, many games in the genre drifted towards action by allowing the option of direct confrontations. The Hitman series, the first installment of which was released in 2000, allowed this play style, but rewarded the player for stealthy and elaborate assassination of antagonists. Hitman: Codename 47, the first of the series, was the first 3D game to employ the genre's device of disguises. No One Lives Forever, an espionage themed parody also released in 2000, again allowed the player to combine or choose between stealth and overt violence. In 2000, the first-person action role-playing game Deus Ex also allowed the player the choice of taking a stealth approach. A USA Today reviewer found "At the easiest difficulty setting, your character is pureed again and again by an onslaught of human and robotic terrorists until you learn the value of stealth."
Metal Gear Solid 2: Sons of Liberty, released 2001 for the PlayStation 2, further evolved the stealth gameplay series. It featured an array of new abilities, including "leaping over and hanging off of railings, opening and hiding in storage lockers," and sneaking up behind enemies to "hold them at gunpoint for items and ammunition." Metal Gear Solid 2 holds a Guinness World Record for being the first stealth game to feature collective artificial intelligence. Metal Gear Solid 2: Sons of Liberty sold 7 million units in sales, followed by Metal Gear Solid with 6 million units.
Later developments: 2002–present
After the mainstream success of the genre, stealth elements became increasingly incorporated into a wide range of video games, with numerous action games using stealth elements in some way or another. In 2002, the first installment of the Tom Clancy licensed Splinter Cell series was released, which attempted to add more realism to the stealth genre both in terms of graphics and in-game equipment. If the player is discovered in Splinter Cell, the guards will often raise a general alarm which can cause a difficulty spike or even result in automatic mission failure. Splinter Cell was notable for its state of the art graphics, including dynamic lighting and shadows. Like Thief, Splinter Cell featured a visibility meter which determined how much light was falling on the character. These effects not only contributed to the atmosphere of the game, but dynamically affected in which areas the player could hide. The 2004 sequel, Tom Clancy's Splinter Cell: Pandora Tomorrow, added a multiplayer component to the stealth genre.
As the genre developed and progressed, stealth gameplay was combined with other genres. Sly Cooper, a cel-shaded game released in 2002, was a "stealth platformer", while 2003's Siren combined the survival horror genre with the stealth genre. In the same year, Manhunt employed a snuff movie theme and allowed the player to kill antagonists with varying levels of violence, dependent on how much time was spent sneaking behind them. It was the first to show visual executions in the genre. The following year, Konami's Metal Gear Acid combined the stealth gameplay of the Metal Gear series with turn-based strategy and tactical role-playing game elements as well as card battle elements from Konami's own Yu-Gi-Oh! games.
In 2004, Metal Gear Solid 3: Snake Eater introduced camouflage to the genre. Set in a jungle, the game emphasized infiltration in a natural environment, along with survival aspects such as food capture, healing and close-quarters combat. The following year, the updated version Metal Gear Solid 3: Subsistence added an online multiplayer mode to the game with stealth elements. Another 2004 release was The Chronicles of Riddick: Escape From Butcher Bay, based on the Chronicles of Riddick series of movies. The game follows the character of Riddick as he attempts to escape from prison. Action and stealth gaming are combined seamlessly by allowing the character to hide, sneak, or fight his way past most situations. The game was critically acclaimed, and was followed with The Chronicles of Riddick: Assault on Dark Athena in 2009.
In 2007, Assassin's Creed employed a social element to the stealth game, where the player is able to hide among crowds of civilians by taking care to blend in. Stealth elements were incorporated into Crytek's open world first-person shooter Crysis, multiplayer first-person shooter Team Fortress 2, and first-person role-playing game Fallout 3. In 2008, Metal Gear Solid 4: Guns of the Patriots (PlayStation 3) introduced a battlezone element, where the stealth gameplay is incorporated into a battlefield fought between two armies, both of which can be infiltrated by Solid Snake. In 2009, Assassin's Creed II broadened its predecessor's elements of stealth by allowing the player to blend among any group of civilians, rather than specific ones. Assassin's Creed II also allowed the player to distract guards by tossing coins or by hiring thieves and courtesans, and also featured a notoriety level, which made the player more recognizable until they paid off officials or tore down wanted posters. The same year, Uncharted 2: Among Thieves and Batman: Arkham Asylum incorporated stealth elements in different segments of the games. The multiplayer modes of Aliens vs. Predator in 2010 and Killzone 3 in 2011 also incorporated stealth elements.
The 2012 game Dishonored tried to incorporate stealth elements that were influenced by Thief, such as the importance of lighting and shadows. The developers later abandoned that system citing realism as a factor. The game instead relies on a system of "occlusion-based" stealth, using the vision cones of the enemies, obstacles, and special abilities which determines whether or not the character is visible. Forbes called Dishonored one of the best stealth games of 2012, along with Hitman: Absolution and Mark of the Ninja. Mark of the Ninja puts a twist on the stealth genre in that it is a 2D side-scroller. This posed some unique factors, such as the lack of corners for the character to hide behind, and the visibility presented in a side-scroller; the developers overcame this by adding 'fog' that prevents the player from seeing things that the character can not see, visually representing enemy line-of-sight and even visualizing the noise made by the character, including how far that noise travels. After the completion of the game, the player has access to a harder difficulty called "New Game Plus", which further decreases visibility by adding fog behind the player and removes noise visualizations and enemy line of sight indicators.
In 2014, Creative Assembly released Alien: Isolation, a stealth game which emphasized survival-horror. In this game, the protagonist is trapped on a space station with an alien xenomorph which they must avoid for the majority of the game, being unable to kill it. The game also uses feedback from the player's microphone to enhance gameplay as the alien is able to hear noises made by the player and can use them to detect their location.
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