Artificial Intelligence (video Games)
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video game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This fee ...
s,
artificial intelligence Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech re ...
(AI) is used to generate responsive, adaptive or intelligent behaviors primarily in
non-player character A non-player character (NPC), or non-playable character, is any character in a game that is not controlled by a player. The term originated in traditional tabletop role-playing games where it applies to characters controlled by the gamemaster o ...
s (NPCs) similar to human-like intelligence. Artificial intelligence has been an integral part of video games since their inception in the 1950s. AI in video games is a distinct subfield and differs from academic AI. It serves to improve the game-player experience rather than machine learning or decision making. During the
golden age of arcade video games The golden age of arcade video games was the period of rapid growth, technological development and cultural influence of arcade video games, from the late 1970s to the early 1980s. The period began with the release of ''Space Invaders'' in 1978, ...
the idea of AI opponents was largely popularized in the form of graduated difficulty levels, distinct movement patterns, and in-game events dependent on the player's input. Modern games often implement existing techniques such as
pathfinding Pathfinding or pathing is the plotting, by a computer application, of the shortest route between two points. It is a more practical variant on solving mazes. This field of research is based heavily on Dijkstra's algorithm for finding the sh ...
and
decision trees A decision tree is a decision support tool that uses a tree-like model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. It is one way to display an algorithm that only contains condit ...
to guide the actions of NPCs. AI is often used in mechanisms which are not immediately visible to the user, such as data mining and procedural-content generation. In general, game AI does not, as might be thought and sometimes is depicted to be the case, mean a realization of an artificial person corresponding to an NPC in the manner of the
Turing test The Turing test, originally called the imitation game by Alan Turing in 1950, is a test of a machine's ability to artificial intelligence, exhibit intelligent behaviour equivalent to, or indistinguishable from, that of a human. Turing propos ...
or an
artificial general intelligence Artificial general intelligence (AGI) is the ability of an intelligent agent to understand or learn any intellectual task that a human being can. It is a primary goal of some artificial intelligence research and a common topic in science fictio ...
.


Overview

The term "game AI" is used to refer to a broad set of
algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algorithms are used as specificat ...
s that also include techniques from
control theory Control theory is a field of mathematics that deals with the control of dynamical systems in engineered processes and machines. The objective is to develop a model or algorithm governing the application of system inputs to drive the system to a ...
,
robotics Robotics is an interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to design machines that can help and assist humans. Robotics integrat ...
,
computer graphics Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great de ...
and
computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...
in general, and so video game AI may often not constitute "true AI" in that such techniques do not necessarily facilitate computer learning or other standard criteria, only constituting "automated computation" or a predetermined and limited set of responses to a predetermined and limited set of inputs. Many industries and corporate voices claim that so-called video game AI has come a long way in the sense that it has revolutionized the way humans interact with all forms of technology, although many expert researchers are skeptical of such claims, and particularly of the notion that such technologies fit the definition of "intelligence" standardly used in the cognitive sciences. Industry voices make the argument that AI has become more versatile in the way we use all technological devices for more than their intended purpose because the AI allows the technology to operate in multiple ways, allegedly developing their own personalities and carrying out complex instructions of the user. However, people in the field of AI have argued that video game AI is not true intelligence, but an advertising buzzword used to describe computer programs that use simple sorting and matching algorithms to create the illusion of intelligent behavior while bestowing software with a misleading aura of scientific or technological complexity and advancement. Since game AI for NPCs is centered on appearance of intelligence and good gameplay within environment restrictions, its approach is very different from that of traditional AI.


History

Game playing was an area of research in AI from its inception. One of the first examples of AI is the computerized game of Nim made in 1951 and published in 1952. Despite being advanced technology in the year it was made, 20 years before
Pong ''Pong'' is a table tennis–themed twitch arcade sports video game, featuring simple two-dimensional graphics, manufactured by Atari and originally released in 1972. It was one of the earliest arcade video games; it was created by Allan Al ...
, the game took the form of a relatively small box and was able to regularly win games even against highly skilled players of the game. In 1951, using the
Ferranti Mark 1 The Ferranti Mark 1, also known as the Manchester Electronic Computer in its sales literature, and thus sometimes called the Manchester Ferranti, was produced by British electrical engineering firm Ferranti Ltd. It was the world's first commer ...
machine of the
University of Manchester , mottoeng = Knowledge, Wisdom, Humanity , established = 2004 – University of Manchester Predecessor institutions: 1956 – UMIST (as university college; university 1994) 1904 – Victoria University of Manchester 1880 – Victoria Univer ...
,
Christopher Strachey Christopher S. Strachey (; 16 November 1916 – 18 May 1975) was a British computer scientist. He was one of the founders of denotational semantics, and a pioneer in programming language design and computer time-sharing.F. J. Corbató, et al. ...
wrote a
checkers Checkers (American English), also known as draughts (; British English), is a group of strategy board games for two players which involve diagonal moves of uniform game pieces and mandatory captures by jumping over opponent pieces. Checkers ...
program and
Dietrich Prinz Dietrich Gunther Prinz (March 29, 1903 – December 1989) was a computer science pioneer, notable for his work on early British computers at Ferranti, and in particular for developing the first limited chess program in 1951. Biography Prinz was bo ...
wrote one for
chess Chess is a board game for two players, called White and Black, each controlling an army of chess pieces in their color, with the objective to checkmate the opponent's king. It is sometimes called international chess or Western chess to disti ...
. These were among the first computer programs ever written.
Arthur Samuel Arthur Lee Samuel (December 5, 1901 – July 29, 1990) was an American pioneer in the field of computer gaming and artificial intelligence. He popularized the term "machine learning" in 1959. The Samuel Checkers-playing Program was among the wo ...
's checkers program, developed in the middle 50s and early 60s, eventually achieved sufficient skill to challenge a respectable amateur. Work on checkers and chess would culminate in the defeat of
Garry Kasparov Garry Kimovich Kasparov (born 13 April 1963) is a Russian chess grandmaster, former World Chess Champion, writer, political activist and commentator. His peak rating of 2851, achieved in 1999, was the highest recorded until being surpassed by ...
by IBM's
Deep Blue Deep Blue may refer to: Film * ''Deep Blues: A Musical Pilgrimage to the Crossroads'', a 1992 documentary film about Mississippi Delta blues music * Deep Blue (2001 film), ''Deep Blue'' (2001 film), a film by Dwight H. Little * Deep Blue (2003 ...
computer in 1997. The first
video game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This fee ...
s developed in the 1960s and early 1970s, like ''
Spacewar! ''Spacewar!'' is a space combat video game developed in 1962 by Steve Russell in collaboration with Martin Graetz, Wayne Wiitanen, Bob Saunders, Steve Piner, and others. It was written for the newly installed DEC PDP-1 minicomputer at the Mas ...
'', ''
Pong ''Pong'' is a table tennis–themed twitch arcade sports video game, featuring simple two-dimensional graphics, manufactured by Atari and originally released in 1972. It was one of the earliest arcade video games; it was created by Allan Al ...
'', and '' Gotcha'' (1973), were games implemented on
discrete logic A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic gate ...
and strictly based on the competition of two players, without AI. Games that featured a
single player A single-player video game is a video game where input from only one player is expected throughout the course of the gaming session. A single-player game is usually a game that can only be played by one person, while "single-player mode" is usuall ...
mode with enemies started appearing in the 1970s. The first notable ones for the
arcade Arcade most often refers to: * Arcade game, a coin-operated game machine ** Arcade cabinet, housing which holds an arcade game's hardware ** Arcade system board, a standardized printed circuit board * Amusement arcade, a place with arcade games * ...
appeared in 1974: the
Taito is a Japanese company that specializes in video games, toys, arcade cabinets and game centers, based in Shinjuku, Tokyo. The company was founded by Michael Kogan in 1953 as the importing vodka, vending machines and jukeboxes into Japan. It b ...
game ''
Speed Race is a 1974 arcade racing video game developed and manufactured by Taito and released under the titles ''Racer'' and ''Wheels'' in North America by distributor Midway Manufacturing in 1975. Designed by Tomohiro Nishikado, the gameplay involves th ...
'' (
racing video game Racing games are a video game genre in which the player participates in a racing competition. They may be based on anything from real-world racing leagues to fantastical settings. They are distributed along a spectrum between more realistic rac ...
) and the
Atari Atari () is a brand name that has been owned by several entities since its inception in 1972. It is currently owned by French publisher Atari SA through a subsidiary named Atari Interactive. The original Atari, Inc. (1972–1992), Atari, Inc., ...
games ''
Qwak ''Qwak'' is a 2D puzzle-platform game developed by Jamie Woodhouse. It was initially released for the BBC Micro and Acorn Electron in 1989 as part of Superior/Acornsoft's ''Play It Again Sam 10'' compilation. An updated and enhanced Amiga vers ...
'' (duck hunting
light gun shooter Light gun shooter, also called light gun game or simply gun game, is a shooter video game genre in which the primary design element is to simulate a shooting gallery by having the player aiming and discharging a gun-shaped controller at a scre ...
) and '' Pursuit'' ( fighter aircraft dogfighting simulator). Two text-based computer games from 1972, '' Hunt the Wumpus'' and ''
Star Trek ''Star Trek'' is an American science fiction media franchise created by Gene Roddenberry, which began with the eponymous 1960s television series and quickly became a worldwide pop-culture phenomenon. The franchise has expanded into vari ...
'', also had enemies. Enemy movement was based on stored patterns. The incorporation of
microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
s would allow more computation and random elements overlaid into movement patterns. It was during the
golden age of video arcade games The golden age of arcade video games was the period of rapid growth, technological development and cultural influence of arcade video games, from the late 1970s to the early 1980s. The period began with the release of ''Space Invaders'' in 1978, ...
that the idea of AI opponents was largely popularized, due to the success of ''
Space Invaders is a 1978 shoot 'em up arcade game developed by Tomohiro Nishikado. It was manufactured and sold by Taito in Japan, and licensed to the Midway division of Bally for overseas distribution. ''Space Invaders'' was the first fixed shooter and set ...
'' (1978), which sported an increasing difficulty level, distinct movement patterns, and in-game events dependent on
hash function A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called ''hash values'', ''hash codes'', ''digests'', or simply ''hashes''. The values are usually u ...
s based on the player's input. ''
Galaxian is a 1979 fixed shooter arcade video game developed and published by Namco. The player assumes control of the Galaxip starfighter in its mission to protect Earth from waves of aliens. Gameplay involves destroying each formation of aliens, wh ...
'' (1979) added more complex and varied enemy movements, including maneuvers by individual enemies who break out of formation. '' Pac-Man'' (1980) introduced AI patterns to
maze games Maze game is a video game genre description first used by journalists during the 1980s to describe any game in which the entire playing field is a maze. Quick player action is required to escape monsters, outrace an opponent, or navigate the maz ...
, with the added quirk of different personalities for each enemy. ''
Karate Champ ''Karate Champ'', known in Japan as , is a 1984 arcade fighting game developed by Technōs Japan (which would later developing 1995 Neo Geo titles '' Voltage Fighter Gowcaizer'' with SNK) and released by Data East. A variety of moves can be per ...
'' (1984) later introduced AI patterns to
fighting game A fighting game, also known as a versus fighting game, is a video game genre, genre of video game that involves combat between two or more players. Fighting game combat often features mechanics such as Blocking (martial arts), blocking, grappli ...
s. ''
First Queen First or 1st is the ordinal form of the number one (#1). First or 1st may also refer to: *World record, specifically the first instance of a particular achievement Arts and media Music * 1$T, American rapper, singer-songwriter, DJ, and rec ...
'' (1988) was a
tactical Tactic(s) or Tactical may refer to: * Tactic (method), a conceptual action implemented as one or more specific tasks ** Military tactics, the disposition and maneuver of units on a particular sea or battlefield ** Chess tactics ** Political tacti ...
action RPG An action role-playing game (often abbreviated action RPG or ARPG) is a subgenre of video games that combines core elements from both the action game and role-playing genre. Definition The games emphasize real-time combat where the player h ...
which featured characters that can be controlled by the computer's AI in following the leader.
Translation
The
role-playing video game A role-playing video game (commonly referred to as simply a role-playing game or RPG, as well as a computer role-playing game or CRPG) is a video game genre where the player controls the actions of a character (or several party members) immers ...
''
Dragon Quest IV ''Dragon Quest IV: Chapters of the Chosen'', titled ''Dragon Warrior IV'' when initially localized to North America, is a role-playing video game, the fourth installment of the ''Dragon Quest'' video game series developed by Chunsoft and publishe ...
'' (1990) introduced a "Tactics" system, where the user can adjust the AI routines of
non-player character A non-player character (NPC), or non-playable character, is any character in a game that is not controlled by a player. The term originated in traditional tabletop role-playing games where it applies to characters controlled by the gamemaster o ...
s during battle, a concept later introduced to the
action role-playing game An action role-playing game (often abbreviated action RPG or ARPG) is a subgenre of video games that combines core elements from both the action game and role-playing genre. Definition The games emphasize real-time combat where the player h ...
genre by ''
Secret of Mana ''Secret of Mana'', originally released in Japan as is a 1993 action role-playing game developed and published by Square (now Square Enix) for the Super Nintendo Entertainment System. It is the sequel to the 1991 game ''Seiken Densetsu'', rele ...
'' (1993). Games like '' Madden Football'', ''
Earl Weaver Baseball Earl Weaver Baseball is a baseball video game (1987) designed by Don Daglow and Eddie Dombrower and published by Electronic Arts. The artificial intelligence for the computer manager was provided by Baseball Hall of Fame member Earl Weaver, then ...
'' and ''
Tony La Russa Baseball ''Tony La Russa Baseball'' is a baseball computer and video game console sports game series (1991-1997), designed by Don Daglow, Michael Breen, Mark Buchignani, David Bunnett and Hudson Piehl and developed by Stormfront Studios. The game appe ...
'' all based their AI in an attempt to duplicate on the computer the coaching or managerial style of the selected celebrity. Madden, Weaver and La Russa all did extensive work with these game development teams to maximize the accuracy of the games. Later sports titles allowed users to "tune" variables in the AI to produce a player-defined managerial or coaching strategy. The emergence of new game genres in the 1990s prompted the use of formal AI tools like finite state machines.
Real-time strategy Real-time strategy (RTS) is a Video game genre, subgenre of strategy video games that do not progress incrementally in turn-based game, turns, but allow all players to play simultaneously, in "real time". By contrast, in Turn-based strategy, turn ...
games taxed the AI with many objects, incomplete information, pathfinding problems, real-time decisions and economic planning, among other things. The first games of the genre had notorious problems. ''
Herzog Zwei (, German for "'' Duke Two''") is a real-time strategy video game developed by Technosoft and published by Sega for the Mega Drive/Genesis. An early real-time strategy game, it predates the genre-popularizing ''Dune II''. It was released first i ...
'' (1989), for example, had almost broken pathfinding and very basic three-state state machines for unit control, and ''
Dune II A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...
'' (1992) attacked the players' base in a beeline and used numerous cheats. Later games in the genre exhibited more sophisticated AI. Later games have used bottom-up AI methods, such as the
emergent behaviour In philosophy, systems theory, science, and art, emergence occurs when an entity is observed to have properties its parts do not have on their own, properties or behaviors that emerge only when the parts interact in a wider whole. Emergence ...
and evaluation of player actions in games like '' Creatures'' or '' Black & White''.
Façade (interactive story) A façade () (also written facade) is generally the front part or exterior of a building. It is a loan word from the French (), which means ' frontage' or 'face'. In architecture, the façade of a building is often the most important aspect ...
was released in 2005 and used interactive multiple way dialogs and AI as the main aspect of game. Games have provided an environment for developing artificial intelligence with potential applications beyond gameplay. Examples include Watson, a
Jeopardy! ''Jeopardy!'' is an American game show created by Merv Griffin. The show is a quiz competition that reverses the traditional question-and-answer format of many quiz shows. Rather than being given questions, contestants are instead given genera ...
-playing computer; and the RoboCup tournament, where robots are trained to compete in soccer.


Views

Many experts complain that the "AI" in the term "game AI" overstates its worth, as game AI is not about
intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can b ...
, and shares few of the objectives of the academic field of AI. Whereas "real AI" addresses fields of machine learning, decision making based on arbitrary data input, and even the ultimate goal of strong AI that can reason, "game AI" often consists of a half-dozen rules of thumb, or
heuristics A heuristic (; ), or heuristic technique, is any approach to problem solving or self-discovery that employs a practical method that is not guaranteed to be optimal, perfect, or rational, but is nevertheless sufficient for reaching an immediate, ...
, that are just enough to give a good gameplay experience. Historically, academic game-AI projects have been relatively separate from commercial products because the academic approaches tended to be simple and non-scalable. Commercial game AI has developed its own set of tools, which have been sufficient to give good performance in many cases. Game developers' increasing awareness of academic AI and a growing interest in computer games by the academic community is causing the definition of what counts as AI in a game to become less
idiosyncratic An idiosyncrasy is an unusual feature of a person (though there are also other uses, see below). It can also mean an odd habit. The term is often used to express eccentricity or peculiarity. A synonym may be "quirk". Etymology The term "idiosyncr ...
. Nevertheless, significant differences between different application domains of AI mean that game AI can still be viewed as a distinct subfield of AI. In particular, the ability to legitimately solve some AI problems in games by
cheating Cheating generally describes various actions designed to subvert rules in order to obtain unfair advantages. This includes acts of bribery, cronyism and nepotism in any situation where individuals are given preference using inappropriate crit ...
creates an important distinction. For example, inferring the position of an unseen object from past observations can be a difficult problem when AI is applied to robotics, but in a computer game a NPC can simply look up the position in the game's
scene graph Scene (from Greek σκηνή ''skēnḗ'') may refer to: Arts, entertainment, and media Music * Scene (subculture), a youth subculture from the early 2000s characterized by a distinct music and style. Groups and performers * The Scene who rec ...
. Such cheating can lead to unrealistic behavior and so is not always desirable. But its possibility serves to distinguish game AI and leads to new problems to solve, such as when and how to cheat. The major limitation to strong AI is the inherent depth of thinking and the extreme complexity of the decision making process. This means that although it would be then theoretically possible to make "smart" AI the problem would take considerable processing power.


Usage


In computer simulations of board games

*
Computer chess Computer chess includes both hardware (dedicated computers) and software capable of playing chess. Computer chess provides opportunities for players to practice even in the absence of human opponents, and also provides opportunities for analysi ...
* Computer shogi *
Computer Go Computer Go is the field of artificial intelligence (AI) dedicated to creating a computer program that plays the traditional board game Go. The field is sharply divided into two eras. Before 2015, the programs of the era were weak. The best ...
* Computer checkers *
Computer Othello Computer Othello refers to computer architecture encompassing computer hardware and computer software capable of playing the game of Othello. It is also known as Reversi for Microsoft Windows (1.0- XP, 1985-2005) and Classic Mac OS (since 1984). ...
*
Computer poker players A computer poker player is a computer program designed to play the game of poker against human opponents or other computer opponents. It is commonly referred to as pokerbot or just simply bot. On the Internet These bots or computer programs a ...
*
Akinator ''Akinator'' is a video game developed by French company Elokence. During gameplay, it attempts to determine what fictional or real-life character, object, or animal the player is thinking of by asking a series of questions (similar to the game ...
*
Computer Arimaa Computer Arimaa refers to the playing of the board game Arimaa by computer programs. In 2002, Indian-American computer engineer Omar Syed published the rules to Arimaa and announced a $10,000 prize, available annually until 2020, for the first co ...
*
Logistello Logistello is a computer program that plays the game Othello, also known as Reversi. Logistello was written by Michael Buro and is regarded as a strong player, having beaten the human world champion Takeshi Murakami six games to none in 1997 &m ...
, which plays
Reversi Reversi is a strategy board game for two players, played on an 8×8 uncheckered board. It was invented in 1883. Othello, a variant with a fixed initial setup of the board, was patented in 1971. Basics There are sixty-four identical game pieces ...
*
Rog-O-Matic Rog-O-Matic is a bot developed in 1981 to play and win the video game ''Rogue'', by four graduate students in the Computer Science Department at Carnegie-Mellon University in Pittsburgh: Andrew Appel, Leonard Hamey, Guy Jacobson and Michael Loren ...
, which plays Rogue * Computer players of Scrabble * A variety of board games in the
Computer Olympiad The Computer Olympiad is a multi-games event in which computer programs compete against each other. For many games, the Computer Olympiads are an opportunity to claim the "world's best computer player" title. First contested in 1989, the majori ...
*
General game playing General game playing (GGP) is the design of artificial intelligence programs to be able to play more than one game successfully. For many games like chess, computers are programmed to play these games using a specially designed algorithm, which ca ...
*
Solved game A solved game is a game whose outcome (win, lose or draw) can be correctly predicted from any position, assuming that both players play perfectly. This concept is usually applied to abstract strategy games, and especially to games with full inform ...
s have a computer strategy which is guaranteed to be optimal, and in some cases force a win or draw.


In modern video games

Game AI/heuristic algorithms are used in a wide variety of quite disparate fields inside a game. The most obvious is in the control of any NPCs in the game, although "scripting" (
decision tree A decision tree is a decision support tool that uses a tree-like model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. It is one way to display an algorithm that only contains condit ...
) is currently the most common means of control. These handwritten decision trees often result in "artificial stupidity" such as repetitive behavior, loss of immersion, or abnormal behavior in situations the developers did not plan for.
Pathfinding Pathfinding or pathing is the plotting, by a computer application, of the shortest route between two points. It is a more practical variant on solving mazes. This field of research is based heavily on Dijkstra's algorithm for finding the sh ...
, another common use for AI, is widely seen in
real-time strategy Real-time strategy (RTS) is a Video game genre, subgenre of strategy video games that do not progress incrementally in turn-based game, turns, but allow all players to play simultaneously, in "real time". By contrast, in Turn-based strategy, turn ...
games. Pathfinding is the method for determining how to get a NPC from one point on a map to another, taking into consideration the terrain, obstacles and possibly "
fog of war The fog of war (german: links=no, Nebel des Krieges) is the uncertainty in situational awareness experienced by participants in military operations. The term seeks to capture the uncertainty regarding one's own capability, adversary capability, ...
".Yannakakis, G. N. (2012, May). Game AI revisited. In Proceedings of the 9th conference on Computing Frontiers (pp. 285–292). ACM. Commercial videogames often use fast and simple "grid-based pathfinding", wherein the terrain is mapped onto a rigid grid of uniform squares and a pathfinding algorithm such as A* or
IDA* Iterative deepening A* (IDA*) is a graph traversal and path search algorithm that can find the shortest path between a designated start node and any member of a set of goal nodes in a weighted graph. It is a variant of iterative deepening depth ...
is applied to the grid. Instead of just a rigid grid, some games use irregular polygons and assemble a
navigation mesh A navigation mesh, or navmesh, is an abstract data structure used in artificial intelligence applications to aid agents in pathfinding through complicated spaces. This approach has been known since at least the mid-1980s in robotics, where it has ...
out of the areas of the map that NPCs can walk to. As a third method, it is sometimes convenient for developers to manually select "waypoints" that NPCs should use to navigate; the cost is that such waypoints can create unnatural-looking movement. In addition, waypoints tend to perform worse than navigation meshes in complex environments.Cui, X., & Shi, H. (2011). A*-based pathfinding in modern computer games. International Journal of Computer Science and Network Security, 11(1), 125-130. Beyond static pathfinding,
navigation Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation, ...
is a sub-field of Game AI focusing on giving NPCs the capability to navigate in a dynamic environment, finding a path to a target while avoiding collisions with other entities (other NPC, players...) or collaborating with them (group navigation). Navigation in dynamic strategy games with large numbers of units, such as Age of Empires (1997) or
Civilization V ''Sid Meier's Civilization V'' is a 4X video game in the ''Civilization'' series developed by Firaxis Games. The game was released on Microsoft Windows on September 21, 2010, on OS X on November 23, 2010, and on Linux on June 10, 2014. In ...
(2010), often performs poorly; units often get in the way of other units. Rather than improve the Game AI to properly solve a difficult problem in the virtual environment, it is often more cost-effective to just modify the scenario to be more tractable. If pathfinding gets bogged down over a specific obstacle, a developer may just end up moving or deleting the obstacle. In
Half-Life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
(1998), the pathfinding algorithm sometimes failed to find a reasonable way for all the NPCs to evade a thrown grenade; rather than allow the NPCs to attempt to bumble out of the way and risk appearing stupid, the developers instead scripted the NPCs to crouch down and cover in place in that situation.


Video game combat AI

Many contemporary video games fall under the category of action,
first-person shooter First-person shooter (FPS) is a sub-genre of shooter video games centered on gun and other weapon-based combat in a first-person perspective, with the player experiencing the action through the eyes of the protagonist and controlling the pl ...
, or adventure. In most of these types of games, there is some level of combat that takes place. The AI's ability to be efficient in combat is important in these genres. A common goal today is to make the AI more human or at least appear so. One of the more positive and efficient features found in modern-day video game AI is the ability to hunt. AI originally reacted in a very black and white manner. If the player were in a specific area then the AI would react in either a complete offensive manner or be entirely defensive. In recent years, the idea of "hunting" has been introduced; in this 'hunting' state the AI will look for realistic markers, such as sounds made by the character or footprints they may have left behind.Schreiner, Tim. "Artificial Intelligence in Game Design." Artificial Intelligence Depot. Web. 19 November 2009
AI-depot.com
These developments ultimately allow for a more complex form of play. With this feature, the player can actually consider how to approach or avoid an enemy. This is a feature that is particularly prevalent in the stealth genre. Another development in recent game AI has been the development of "survival instinct". In-game computers can recognize different objects in an environment and determine whether it is beneficial or detrimental to its survival. Like a user, the AI can look for cover in a firefight before taking actions that would leave it otherwise vulnerable, such as reloading a weapon or throwing a grenade. There can be set markers that tell it when to react in a certain way. For example, if the AI is given a command to check its health throughout a game then further commands can be set so that it reacts a specific way at a certain percentage of health. If the health is below a certain threshold then the AI can be set to run away from the player and avoid it until another function is triggered. Another example could be if the AI notices it is out of bullets, it will find a cover object and hide behind it until it has reloaded. Actions like these make the AI seem more human. However, there is still a need for improvement in this area. Another side-effect of combat AI occurs when two AI-controlled characters encounter each other; first popularized in the
id Software id Software LLC () is an American video game developer based in Richardson, Texas. It was founded on February 1, 1991, by four members of the computer company Softdisk: game programmer, programmers John Carmack and John Romero, game designer T ...
game ''
Doom Doom is another name for damnation. Doom may also refer to: People * Doom (professional wrestling), the tag team of Ron Simmons and Butch Reed * Daniel Doom (born 1934), Belgian cyclist * Debbie Doom (born 1963), American softball pitcher * ...
'', so-called 'monster infighting' can break out in certain situations. Specifically, AI agents that are programmed to respond to hostile attacks will sometimes attack ''each other'' if their cohort's attacks land too close to them. In the case of ''Doom'', published gameplay manuals even suggest taking advantage of monster infighting in order to survive certain levels and difficulty settings.


Monte Carlo tree search method

Game AI often amounts to pathfinding and finite state machines. Pathfinding gets the AI from point A to point B, usually in the most direct way possible. State machines permit transitioning between different behaviors. The
Monte Carlo tree search In computer science, Monte Carlo tree search (MCTS) is a heuristic search algorithm for some kinds of decision processes, most notably those employed in software that plays board games. In that context MCTS is used to solve the game tree. MCT ...
method provides a more engaging game experience by creating additional obstacles for the player to overcome. The MCTS consists of a tree diagram in which the AI essentially plays
tic-tac-toe Tic-tac-toe (American English), noughts and crosses (Commonwealth English), or Xs and Os (Canadian or Irish English) is a paper-and-pencil game for two players who take turns marking the spaces in a three-by-three grid with ''X'' or ''O''. ...
. Depending on the outcome, it selects a pathway yielding the next obstacle for the player. In complex video games, these trees may have more branches, provided that the player can come up with several strategies to surpass the obstacle. In this 2022 year's survey, you can learn about recent applications of the MCTS algorithm in various game domains such as perfect-information combinatorial games, strategy games (including ''
RTS RTS may refer to: Medicine * Rape trauma syndrome, the psychological trauma experienced by a rape victim * Revised Trauma Score, a system to evaluate injuries secondary to violent trauma * Rubinstein–Taybi syndrome, a condition characterized by ...
''), card games etc.


Uses in games beyond NPCs

Academic AI may play a role within Game AI, outside the traditional concern of controlling NPC behavior.
Georgios N. Yannakakis Georgios N. Yannakakis is Director and Professor at the Institute of Digital Games, University of Malta and Editor-in-Chief of IEEE Transactions on Games. He is one of the leading researchers within player affective modelling and adaptive content ...
highlighted four potential application areas: #
Player-experience modeling In online marketing, a landing page, sometimes known as a "lead capture page", "single property page", "static page", "squeeze page" or a "destination page", is a single web page that appears in response to clicking on a search engine optimized se ...
: Discerning the ability and emotional state of the player, so as to tailor the game appropriately. This can include
dynamic game difficulty balancing Dynamic game difficulty balancing (DGDB), also known as dynamic difficulty adjustment (DDA) or dynamic game balancing (DGB), is the process of automatically changing parameters, scenarios, and behaviors in a video game in real-time, based on the pl ...
, which consists in adjusting the difficulty in a video game in real-time based on the player's ability. Game AI may also help deduce player intent (such as
gesture recognition Gesture recognition is a topic in computer science and language technology with the goal of interpreting human gestures via mathematical algorithms. It is a subdiscipline of computer vision. Gestures can originate from any bodily motion or sta ...
). # Procedural-content generation: Creating elements of the game environment like environmental conditions, levels, and even music in an automated way. AI methods can generate new content or interactive stories. # Data mining on user behavior: This allows game designers to explore how people use the game, what parts they play most, and what causes them to stop playing, allowing developers to tune gameplay or improve monetization. # Alternate approaches to NPCs: These include changing the game set-up to enhance NPC believability and exploring social rather than individual NPC behavior. Rather than procedural generation, some researchers have used
generative adversarial network A generative adversarial network (GAN) is a class of machine learning frameworks designed by Ian Goodfellow and his colleagues in June 2014. Two neural networks contest with each other in the form of a zero-sum game, where one agent's gain is a ...
s (GANs) to create new content. In 2018 researchers at Cornwall University trained a GAN on a thousand human-created levels for
DOOM Doom is another name for damnation. Doom may also refer to: People * Doom (professional wrestling), the tag team of Ron Simmons and Butch Reed * Daniel Doom (born 1934), Belgian cyclist * Debbie Doom (born 1963), American softball pitcher * ...
(1993); following training, the neural net prototype was able to design new playable levels on its own. Similarly, researchers at the
University of California The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Francisco, ...
prototyped a GAN to generate levels for
Super Mario (also known as and ) is a platform game series created by Nintendo starring their mascot, Mario. It is the central series of the greater Mario (franchise), ''Mario'' franchise. At least one ''Super Mario'' game has been released for every m ...
. In 2020 Nvidia displayed a GAN-created clone of '' Pac-Man''; the GAN learned how to recreate the game by watching 50,000 (mostly bot-generated) playthroughs.


Cheating AI

In the context of artificial intelligence in video games, cheating refers to the programmer giving agents actions and access to information that would be unavailable to the player in the same situation. Believing that the Atari 8-bit could not compete against a human player, Chris Crawford did not fix a bug in ''
Eastern Front (1941) ''Eastern Front (1941)'' is a computer wargame for the Atari 8-bit family created by Chris Crawford and published through the Atari Program Exchange (APX) in 1981. A scenario editor and assembly language source code for the game were also s ...
'' that benefited the computer-controlled Russian side. ''Computer Gaming World'' in 1994 reported that "It is a well-known fact that many AIs 'cheat' (or, at least, 'fudge') in order to be able to keep up with human players". For example, if the agents want to know if the player is nearby they can either be given complex, human-like sensors (seeing, hearing, etc.), or they can cheat by simply asking the
game engine A game engine is a software framework primarily designed for the development of video games and generally includes relevant libraries and support programs. The "engine" terminology is similar to the term "software engine" used in the software i ...
for the player's position. Common variations include giving AIs higher speeds in racing games to catch up to the player or spawning them in advantageous positions in first-person shooters. The use of cheating in AI shows the limitations of the "intelligence" achievable artificially; generally speaking, in games where strategic creativity is important, humans could easily beat the AI after a minimum of trial and error if it were not for this advantage. Cheating is often implemented for performance reasons where in many cases it may be considered acceptable as long as the effect is not obvious to the player. While cheating refers only to privileges given specifically to the AI—it does not include the inhuman swiftness and precision natural to a computer—a player might call the computer's inherent advantages "cheating" if they result in the agent acting unlike a human player.
Sid Meier Sidney K. Meier ( ; born February 24, 1954) is a Canadian-American programmer, game designer, designer, and video game producer, producer of several strategy video games and simulation video games, including the ''Civilization (series), Civiliz ...
stated that he omitted multiplayer alliances in ''
Civilization A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). Ci ...
'' because he found that the computer was almost as good as humans in using them, which caused players to think that the computer was cheating. Developers say that most game AIs are honest but they dislike players erroneously complaining about "cheating" AI. In addition, humans use tactics against computers that they would not against other people.


Examples

In the 1996 game '' Creatures'', the user "hatches" small furry animals and teaches them how to behave. These "Norns" can talk, feed themselves, and protect themselves against vicious creatures. It was the first popular application of machine learning in an interactive simulation. Neural networks are used by the creatures to learn what to do. The game is regarded as a breakthrough in artificial life research, which aims to model the behavior of creatures interacting with their environment.AiGameDev - Top 10 Most Influential AI Games
/ref> In the 2001
first-person shooter First-person shooter (FPS) is a sub-genre of shooter video games centered on gun and other weapon-based combat in a first-person perspective, with the player experiencing the action through the eyes of the protagonist and controlling the pl ...
'' Halo: Combat Evolved'' the player assumes the role of the Master Chief, battling various aliens on foot or in vehicles. Enemies use cover very wisely, and employ suppressing fire and grenades. The squad situation affects the individuals, so certain enemies flee when their leader dies. Attention is paid to the little details, with enemies notably throwing back grenades or team-members responding to being bothered. The underlying "behavior tree" technology has become very popular in the games industry since ''
Halo 2 ''Halo 2'' is a 2004 first-person shooter game developed by Bungie and published by Microsoft Game Studios for the Xbox console. ''Halo 2'' is the second installment in the ''Halo'' franchise and the sequel to 2001's critically acclaimed '' ...
''. The 2005
psychological horror Psychological horror is a genre, subgenre of horror fiction, horror and psychological fiction with a particular focus on mental, emotional, and Mental state, psychological states to frighten, disturb, or unsettle its audience. The subgenre frequent ...
first-person shooter '' F.E.A.R.'' has player characters engage a
battalion A battalion is a military unit, typically consisting of 300 to 1,200 soldiers commanded by a lieutenant colonel, and subdivided into a number of companies (usually each commanded by a major or a captain). In some countries, battalions are ...
of cloned super-soldiers, robots and paranormal creatures. The AI uses a planner to generate context-sensitive behaviors, the first time in a mainstream game. This technology is still used as a reference for many studios. The Replicas are capable of utilizing the game environment to their advantage, such as overturning tables and shelves to create cover, opening doors, crashing through windows, or even noticing (and alerting the rest of their comrades to) the player's flashlight. In addition, the AI is also capable of performing flanking maneuvers, using suppressing fire, throwing grenades to flush the player out of cover, and even playing dead. Most of these actions, in particular the flanking, is the result of emergent behavior. The
survival horror Survival horror is a subgenre of survival of the players as the game tries to frighten them with either horror graphics or scary ambience. Although combat can be part of the gameplay, the player is made to feel less in control than in typical ac ...
series ''
S.T.A.L.K.E.R. ''S.T.A.L.K.E.R.'' is a first-person-shooter survival horror video game series developed by GSC Game World. The series is set in an alternate version of the present-day Chernobyl Exclusion Zone in Ukraine, where, according to the series' backs ...
'' (2007–) confronts the player with man-made experiments, military soldiers, and mercenaries known as Stalkers. The various encountered enemies (if the difficulty level is set to its highest) use combat tactics and behaviors such as healing wounded allies, giving orders, out-flanking the player and using weapons with pinpoint accuracy. The 2010
real-time strategy Real-time strategy (RTS) is a Video game genre, subgenre of strategy video games that do not progress incrementally in turn-based game, turns, but allow all players to play simultaneously, in "real time". By contrast, in Turn-based strategy, turn ...
game '' StarCraft II: Wings of Liberty'' gives the player control of one of three factions in a 1v1, 2v2, or 3v3 battle arena. The player must defeat their opponents by destroying all their units and bases. This is accomplished by creating units that are effective at countering opponents' units. Players can play against multiple different levels of AI difficulty ranging from very easy to Cheater 3 (insane). The AI is able to cheat at the difficulty Cheater 1 (vision), where it can see units and bases when a player in the same situation could not. Cheater 2 gives the AI extra resources, while Cheater 3 gives an extensive advantage over its opponent.


See also

*
Applications of artificial intelligence Artificial intelligence (AI) has been used in applications to alleviate certain problems throughout industry and academia. AI, like electricity or computers, is a general purpose technology that has a multitude of applications. It has been used ...
* Behavior model *
Machine learning in video games In video games, various artificial intelligence techniques have been used in a variety of ways, ranging from non-player character (NPC) control to procedural content generation (PCG). Machine learning is a subset of artificial intelligence that f ...
*
Video game bot In video games, a bot is a type of artificial intelligence (AI)–based expert system software that plays a video game in the place of a human. Bots are used in a variety of video game genres for a variety of tasks: a bot written for a first-per ...
* Simulated reality *
Utility system In video game AI, a utility system, or utility AI, is a simple but effective way to model behaviors for non-player characters. Using numbers, formulas, and scores to rate the relative benefit of possible actions, one can assign utilities to each a ...
- a robust technique for decision making in video games *
Kynapse Kynapse is the artificial intelligence middleware product, developed by Kynogon, which was bought by Autodesk in 2008 and called ''Autodesk Kynapse''. In 2011, it has been re-engineered and rebranded ''Autodesk Navigation''. Since the discontinua ...
– game AI middleware, specializing in path finding and spatial reasoning *
AiLive AiLive Inc. (formerly iKuni) is a software company based in Mountain View, California, Mountain View, California. The company was co-founded in 2000 by software programmer and developer Wei Yen and by computer engineer Xiaoyuan Tu. The company has ...
– A suite of game AI middleware * xaitment – graphical game AI software ; Lists * List of emerging technologies *
List of game AI middleware Middleware for games is a piece of software that is integrated into a game engine to handle some specialized aspect of it, such as game physics, physics, computer graphics, graphics or computer network, networking. Notable * Autodesk Gameware - f ...
*
Outline of artificial intelligence The following outline is provided as an overview of and topical guide to artificial intelligence: Artificial intelligence (AI) – intelligence exhibited by machines or software. It is also the name of the scientific field which studies how to ...


References


Bibliography

* Bogost, Ian (2017). "'Artificial Intelligence' Has Become Meaningless.

* Bourg; Seemann (2004). ''AI for Game Developers''.
O'Reilly & Associates O'Reilly Media (formerly O'Reilly & Associates) is an American learning company established by Tim O'Reilly that publishes books, produces tech conferences, and provides an online learning platform. Its distinctive brand features a woodcut of a ...
. . * Buckland (2002). ''AI Techniques for Game Programming''. Muska & Lipman. . * Buckland (2004)
''Programming Game AI By Example''
Wordware Publishing. . * Champandard (2003)
''AI Game Development''
New Riders. . * Eaton, Eric ''et al.'' (2015). "Who speaks for AI?

* Funge (1999). ''AI for Animation and Games: A Cognitive Modeling Approach''.
A K Peters A K Peters, Ltd. was a publisher of scientific and technical books, specializing in mathematics and in computer graphics, robotics, and other fields of computer science. They published the journals ''Experimental Mathematics'' and the ''Journal ...
. . * Funge (2004)
''Artificial Intelligence for Computer Games: An Introduction''
A K Peters. . * Kaplan, Jerry (2017). "AI's PR Problem.

* Millington (2005)
''Artificial Intelligence for Games''
. Morgan Kaufmann. . * Schwab (2004). ''AI Game Engine Programming''. Charles River Media. . * Smed and Hakonen (2006)
''Algorithms and Networking for Computer Games''
John Wiley & Sons John Wiley & Sons, Inc., commonly known as Wiley (), is an American multinational publishing company founded in 1807 that focuses on academic publishing and instructional materials. The company produces books, journals, and encyclopedias, in p ...
. .


External links


Special Interest Group on Artificial Intelligence @IGDA

AI Game Programming Wisdom
on aiwisdom.com
Georgios N. Yannakakis and Julian Togelius
{{Game design Video game development