A game engine is a
software framework
In computer programming, a software framework is an abstraction in which software, providing generic functionality, can be selectively changed by additional user-written code, thus providing application-specific software. It provides a standard ...
primarily designed for the development of
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, game controller, controller, computer keyboard, keyboard, or motion sensing device to gener ...
s and generally includes relevant
libraries
A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vir ...
and support programs. The "engine" terminology is similar to the term "
software engine
A software engine is a core component of a complex software system. Alternate phrases include "software core" and "software core engine", or just "core engine".
The word "engine" is a metaphor of a car's engine. Thus a software engine is a comp ...
" used in the
software industry
The software industry includes businesses for development, maintenance and publication of software that are using different business models, mainly either "license/maintenance based" (on-premises) or "Cloud based" (such as SaaS, PaaS, IaaS, MBaa ...
.
The game engine can also refer to the development software utilizing this framework, typically offering a suite of tools and features for developing games.
Developers can use game engines to construct games for
video game consoles
A video game console is an electronic device that outputs a video signal or image to display a video game that can be played with a game controller. These may be home consoles, which are generally placed in a permanent location connected to a ...
and other types of
computers. The core functionality typically provided by a game engine may include a
rendering engine ("renderer") for
2D or
3D graphics
Graphics () are visual images or designs on some surface, such as a wall, canvas, screen, paper, or stone, to inform, illustrate, or entertain. In contemporary usage, it includes a pictorial representation of data, as in design and manufacture, ...
, a
physics engine
A physics engine is computer software that provides an approximate simulation of certain physical systems, such as rigid body dynamics (including collision detection), soft body dynamics, and fluid dynamics, of use in the domains of computer ...
or
collision detection
Collision detection is the computational problem of detecting the intersection (Euclidean geometry), intersection of two or more objects. Collision detection is a classic issue of computational geometry and has applications in various computing ...
(and collision response),
sound
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by ...
,
scripting,
animation,
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 r ...
,
networking, streaming,
memory management
Memory management is a form of resource management applied to computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when ...
,
threading,
localization support,
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 recor ...
, and video support for
cinematics. Game engine implementers often economize on the process of
game development
Video game development (or gamedev) is the process of developing a video game. The effort is undertaken by a developer, ranging from a single person to an international team dispersed across the globe. Development of traditional commercial PC ...
by reusing/adapting, in large part, the same game engine to produce different games
or to aid in
porting
In software engineering, porting is the process of adapting software for the purpose of achieving some form of execution in a computing environment that is different from the one that a given program (meant for such execution) was originally des ...
games to multiple platforms.
Purpose

In many cases, game engines provide a suite of visual
development tools
A programming tool or software development tool is a computer program that software developers use to create, debug, maintain, or otherwise support other programs and applications. The term usually refers to relatively simple programs, that can ...
in addition to reusable software components. These tools are generally provided in an
integrated development environment
An integrated development environment (IDE) is a software application that provides comprehensive facilities to computer programmers for software development. An IDE normally consists of at least a source code editor, build automation tools a ...
to enable simplified,
rapid development of games in a
data-driven manner. Game-engine developers often attempt to preempt implementer needs by developing
robust
Robustness is the property of being strong and healthy in constitution. When it is transposed into a system, it refers to the ability of tolerating perturbations that might affect the system’s functional body. In the same line ''robustness'' ca ...
software suites which include many elements a game developer may need to build a game. Most game-engine suites provide facilities that ease development, such as graphics, sound, physics and
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 ...
(AI) functions. These game engines are sometimes called "
middleware
Middleware is a type of computer software that provides services to software applications beyond those available from the operating system. It can be described as "software glue".
Middleware makes it easier for software developers to implement c ...
" because, as with the
business sense of the term, they provide a flexible and reusable software platform which provides all the core functionality needed, right
out of the box, to develop a game application while reducing costs, complexities, and time-to-market — all critical factors in the highly competitive
video-game industry
The video game industry encompasses the Video game development, development, marketing, and Video game monetization, monetization of video games. The industry (economics), industry encompasses dozens of job disciplines and thousands of jobs wor ...
.
Like other types of middleware, game engines usually provide
platform
Platform may refer to:
Technology
* Computing platform, a framework on which applications may be run
* Platform game, a genre of video games
* Car platform, a set of components shared by several vehicle models
* Weapons platform, a system ...
abstraction
Abstraction in its main sense is a conceptual process wherein general rules and concepts are derived from the usage and classification of specific examples, literal ("real" or " concrete") signifiers, first principles, or other methods.
"An a ...
, allowing the same game to run on various
platforms (including
game consoles
A video game console is an electronic device that outputs a video signal or image to display a video game that can be played with a game controller. These may be home consoles, which are generally placed in a permanent location connected to a ...
and personal computers) with few, if any, changes made to the game
source-code
In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the ...
. Often, programmers design game engines with a
component-based architecture that allows specific systems in the engine to be replaced or extended with more specialized (and often more expensive) game-middleware components. Some game engines comprise a series of loosely connected game middleware components that can be selectively combined to create a custom engine, instead of the more common approach of extending or customizing a flexible integrated product. However achieved,
extensibility
Extensibility is a software engineering and systems design principle that provides for future growth. Extensibility is a measure of the ability to extend a system and the level of effort required to implement the extension. Extensions can be t ...
remains a high priority for game engines due to the wide variety of uses for which they are applied. Despite the specificity of the name "game engine", end-users often re-purpose game engines for other kinds of interactive applications with
real-time graphical requirements - such as
marketing demos,
architectural visualization
Architectural rendering, architectural illustration, or architectural visualization is the art of creating three-dimensional images or animations showing the attributes of a proposed architectural design.
Computer generated renderings
Images tha ...
s,
training simulation
In business, training simulation is a virtual medium through which various types of skills can be acquired. Training simulations can be used in a variety of genres; however they are most commonly used in corporate situations to improve business aw ...
s, and
model
A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure.
Models c ...
ing environments.
Some game engines only provide
real-time 3D rendering capabilities instead of the wide range of functionality needed by games. These engines rely upon the
game developer to implement the rest of this functionality or to assemble it from other game-middleware components. These types of engines are generally referred to as a "graphics engine", "rendering engine", or "3D engine" instead of the more encompassing term "game engine". This terminology is inconsistently used, as many full-featured 3D game engines are referred to simply as "3D engines". Examples of graphics engines include:
Crystal Space
Crystal Space is a framework for developing 3D computer graphics, 3D software, applications written in C++ by Jorrit Tyberghein and others. The first public release was on August 26, 1997. It is typically used as a game engine but the framework i ...
,
Genesis3D,
Irrlicht
Irrlicht may refer to:
* Irrlicht, the German name for will-o'-the-wisp, the ghostly light sometimes seen at night over bogs and swamps
* "Irrlicht", the ninth song in the '' Winterreise'' cycle by Franz Schubert
* ''Irrlicht'' (album), by Klau ...
,
OGRE
An ogre ( feminine: ogress) is a legendary monster depicted as a large, hideous, man-like being that eats ordinary human beings, especially infants and children. Ogres frequently feature in mythology, folklore, and fiction throughout the wor ...
,
RealmForge,
Truevision3D, and
Vision Engine
Havok Vision Game Engine is a discontinued, cross-platform, 3D game engine originally authored by Trinigy and later acquired by Havok. It was first released in 2003, and saw its final release in 2014. As of its eighth version, available target ...
. Modern game- or graphics-engines generally provide a
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 recor ...
- an object-oriented representation of the 3D game-world which often simplifies game design and can be used for more efficient rendering of vast virtual worlds.
As technology ages, the components of an engine may become outdated or insufficient for the requirements of a given
project
A project is any undertaking, carried out individually or collaboratively and possibly involving research or design, that is carefully planned to achieve a particular goal.
An alternative view sees a project managerially as a sequence of even ...
. Since the complexity of programming an entirely new engine may result in unwanted delays (or necessitate that a project restart from the beginning), an engine-development team may elect to update their existing engine with newer functionality or components.
History

Before game engines, games were typically written as singular entities: a game for the
Atari 2600
The Atari 2600, initially branded as the Atari Video Computer System (Atari VCS) from its release until November 1982, is a home video game console developed and produced by Atari, Inc. Released in September 1977, it popularized microprocess ...
, for example, had to be designed from the bottom up to make optimal use of the display hardware—this core display routine is today called the
kernel
Kernel may refer to:
Computing
* Kernel (operating system), the central component of most operating systems
* Kernel (image processing), a matrix used for image convolution
* Compute kernel, in GPGPU programming
* Kernel method, in machine lea ...
by developers of games for older systems. Other platforms had more leeway, but even when the display was not a concern, memory constraints usually sabotaged attempts to create the data-heavy design that an engine needs. Even on more accommodating platforms, very little could be reused between games. The rapid advance of
arcade hardware—which was the leading edge of the market at the time—meant that most of the code would have to be thrown out afterwards anyway, as later generations of games would use completely different game designs that took advantage of extra resources. Thus most game designs through the 1980s were designed through a hard-coded rule set with a small number of levels and graphics data. Since 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, ...
, it became common for
video game companies to develop in-house game engines for use with first-party software.
A notable example of an in-house game engine on
home consoles
A home video game console is a video game console that is designed to be connected to a display device, such as a television, and an external power source as to play video games. Home consoles are generally less powerful and customizable than ...
in the mid-1980s was the smooth
side-scrolling engine developed by
Shigeru Miyamoto
is a Japanese video game designer, producer and game director at Nintendo, where he serves as one of its representative directors. Widely regarded as one of the most accomplished and influential designers in the history of video games, he i ...
's team at
Nintendo for the
Nintendo Entertainment System
The Nintendo Entertainment System (NES) is an 8-bit third-generation home video game console produced by Nintendo. It was first released in Japan in 1983 as the commonly known as the The NES, a redesigned version, was released in American ...
(NES). The engine they had developed for the side-scrolling
racing 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 ra ...
''
Excitebike
is a motocross racing video game developed and published by Nintendo. In Japan, it was released for the Famicom in 1984 and then ported to arcades as ''Vs. Excitebike'' for the Nintendo Vs. System later that year. In North America, it was i ...
'' (1984) was later employed for the scrolling
platformer
A platform game (often simplified as platformer and sometimes called a jump 'n' run game) is a sub-genre of action video games in which the core objective is to move the player character between points in an environment. Platform games are charact ...
''
Super Mario Bros.
is a platform game developed and published by Nintendo for the Nintendo Entertainment System (NES). The successor to the 1983 arcade game ''Mario Bros.'' and the first game in the ''Super Mario'' series, it was first released in 1985 for th ...
'' (1985). This had the effect of allowing
Mario
is a character created by Japanese video game designer Shigeru Miyamoto. He is the title character of the '' Mario'' franchise and the mascot of Japanese video game company Nintendo. Mario has appeared in over 200 video games since his c ...
to smoothly
accelerate
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the ...
from a walk to a run, rather than move at a constant speed like in earlier platformers.
While third-party game engines were not common up until the rise of
3D computer graphics
3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for t ...
in the 1990s, there were several 2D
game creation system
A game creation system (GCS) is a consumer-targeted game engine and a set of specialized design tools (and sometimes a light scripting language), engineered for the rapid iteration of user-derived video games. Examples include Novashell and Pie i ...
s produced in the 1980s for
independent video game development
An indie game, short for independent video game, is a video game typically created by individuals or smaller development teams without the financial and technical support of a large game publisher, in contrast to most "AAA" (triple-A) games. ...
. These include ''
Pinball Construction Set'' (1983),
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because ...
's ''War Game Construction Kit'' (1983), ''
Thunder Force Construction'' (1984), ''
Adventure Construction Set
An adventure is an exciting experience or undertaking that is typically bold, sometimes risky. Adventures may be activities with danger such as traveling, exploring, skydiving, mountain climbing, scuba diving, river rafting, or other extreme s ...
'' (1984),
Garry Kitchen's GameMaker (1985), ''
Wargame Construction Set
''Wargame Construction Set'' is a video game game creation system published in 1986 by Strategic Simulations. Developed by Roger Damon, it allows the user to construct, edit and play customizable wargame scenarios. It was released for the Amiga, A ...
'' (1986), ''
Shoot-'Em-Up Construction Kit'' (1987), ''
Arcade Game Construction Kit'' (1988), and most popularly ASCII's ''
RPG Maker
RPG Maker, known in Japan as , is a series of programs for the development of role-playing video games (RPGs) with story-driven elements, created by the Japanese group ASCII, succeeded by Enterbrain. The Japanese name, ''Tsukūru'', is a pu ...
'' engines from 1998 onward. Klik & Play (1994) is another legacy offering that's still available.
The term "game engine" arose in the mid-1990s, especially in connection with 3D games such as
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 ...
s with a
first-person shooter engine. Epic games, founded by developer Tim Sweeney, debuted Unreal Engine in the year 1998.
Such was the popularity of
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 ...
's ''
Doom'' and ''
Quake'' games that, rather than work from scratch, other
developers licensed the core portions of the software and designed their own graphics, characters, weapons and
level
Level or levels may refer to:
Engineering
*Level (instrument), a device used to measure true horizontal or relative heights
*Spirit level, an instrument designed to indicate whether a surface is horizontal or vertical
* Canal pound or level
* Re ...
s—the "game content" or "game assets". Separation of game-specific rules and data from basic concepts like
collision detection
Collision detection is the computational problem of detecting the intersection (Euclidean geometry), intersection of two or more objects. Collision detection is a classic issue of computational geometry and has applications in various computing ...
and game entity meant that teams could grow and specialize.
Later games, such as
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 ...
's ''
Quake III Arena
''Quake III Arena'' is a 1999 multiplayer-focused first-person shooter developed by id Software. The third installment of the ''Quake'' series, ''Arena'' differs from previous games by excluding a story-based single-player mode and focusing prima ...
'' and
Epic Games
Epic Games, Inc. is an American video game and software developer and publisher based in Cary, North Carolina. The company was founded by Tim Sweeney as Potomac Computer Systems in 1991, originally located in his parents' house in Potomac, ...
's 1998 ''
Unreal'' were designed with this approach in mind, with the engine and content developed separately. The practice of licensing such
technology
Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, scie ...
has proved to be a useful auxiliary revenue stream for some game developers, as one license for a high-end commercial game engine can range from US$10,000 to millions of dollars, and the number of licensees can reach several dozen companies, as seen with the
Unreal Engine
Unreal Engine (UE) is a 3D computer graphics game engine developed by Epic Games, first showcased in the 1998 first-person shooter game '' Unreal''. Initially developed for PC first-person shooters, it has since been used in a variety of genr ...
. At the very least, reusable engines make developing game sequels faster and easier, which is a valuable advantage in the competitive
video game industry
The video game industry encompasses the Video game development, development, marketing, and Video game monetization, monetization of video games. The industry (economics), industry encompasses dozens of job disciplines and thousands of jobs wor ...
. While there was a strong rivalry between Epic and id around 2000, since then Epic's
Unreal Engine
Unreal Engine (UE) is a 3D computer graphics game engine developed by Epic Games, first showcased in the 1998 first-person shooter game '' Unreal''. Initially developed for PC first-person shooters, it has since been used in a variety of genr ...
has been far more popular than
id Tech 4
id Tech 4, popularly known as the ''Doom 3'' engine, is a game engine developed by id Software and first used in the video game ''Doom 3''. The engine was designed by John Carmack, who also created previous game engines, such as those for '' Do ...
and its successor
id Tech 5
id Tech 5 is a proprietary game engine developed by id Software. It followed its predecessors, id Tech 1, 2, 3 and 4, all of which had subsequently been published under the GNU General Public License. It was seen as a major advancement over i ...
.
Modern game engines are some of the most complex applications written, often featuring dozens of finely tuned systems interacting to ensure a precisely controlled user experience. The continued evolution of game engines has created a strong separation between rendering, scripting, artwork, and
level design
In video games, a level (also referred to as a map, stage, or round in some older games) is any space available to the player during the course of completion of an objective. Video game levels generally have progressively-increasing difficulty t ...
. It is now common, for example, for a typical game development team to have several times as many artists as actual programmers.
First-person shooter games remain the predominant users of third-party game engines, but they are now also being used in other
genres
Genre () is any form or type of communication in any mode (written, spoken, digital, artistic, etc.) with socially-agreed-upon conventions developed over time. In popular usage, it normally describes a category of literature, music, or other for ...
. For example, 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 ...
''The Elder Scrolls III: Morrowind'' and the MMORPG ''Dark Age of Camelot'' are based on the Gamebryo engine, and the MMORPG ''Lineage II'' is based on the Unreal Engine. Game engines are used for games originally developed for home consoles as well; for example, the RenderWare engine is used in the ''Grand Theft Auto'' and ''Burnout (game), Burnout'' franchises.
Thread (computer science), Threading is taking on more importance due to modern multi-core systems (e.g. Cell (microprocessor), Cell) and increased demands in realism. Typical threads involve rendering, streaming, audio, and physics. Racing games have typically been at the forefront of threading with the physics engine running in a separate thread long before other core subsystems were moved, partly because rendering and related tasks need updating at only 30–60 Hz. For example, on PlayStation 3, physics ran in ''Need For Speed'' at 100 Hz versus ''Forza Motorsport 2'' at 360 Hz.
Although the term was first used in the 1990s, there are a few earlier systems in the 1980s that are also considered to be game engines, such as Sierra's Adventure Game Interpreter (AGI) and SCI systems, LucasArts' SCUMM system and Incentive Software's Freescape engine (in 1986). Unlike most modern game engines, these game engines were never used in any third-party products (except for the SCUMM system which was licensed to and used by Humongous Entertainment).
As game engine technology matures and becomes more user-friendly, the application of game engines has broadened in scope. They are now being used for serious games: visualization, training, medical, and military simulation applications, with the CryEngine being one example. To facilitate this accessibility, new hardware platforms are now being targeted by game engines, including mobile phones (e.g. Android (operating system), Android phones, iPhone) and web browsers (e.g. WebGL, Adobe Shockwave, Shockwave, Adobe Flash, Flash, Trinigy's WebVision, Silverlight, Unity Web Player, O3D and pure DHTML).
Additionally, more game engines are being built upon high-level programming language, higher level languages such as Java (programming language), Java and C Sharp (programming language), C#/.NET Framework, .NET (e.g. Torque Game Engine, TorqueX, and Visual3D.NET), Python (Panda3D), or Lua (programming language), Lua Script (Leadwerks). As most 3D rich games are now mostly GPU-limited (i.e. limited by the power of the graphics card), the potential slowdown due to translation overheads of higher level languages becomes negligible, while the productivity gains offered by these languages work to the game engine developers' benefit. These recent trends are being propelled by companies such as Microsoft to support independent game development, indie game development. Microsoft developed Microsoft XNA, XNA as the SDK of choice for all video games released on Xbox and related products. This includes the Xbox Live Indie Games channel designed specifically for smaller developers who don't have the extensive resources necessary to box games for sale on retail shelves. It is becoming easier and cheaper than ever to develop game engines for platforms that support managed code, managed frameworks.
Game engines as an industry
Producers of game engines decide how they allow users to utilize their products. Just as Video game industry, gaming is an industry, so are the engines they are built off. The major game engines come at varying prices, whether it be in the form of subscription fees or license payments. The Unity (game engine), Unity engine and the
Unreal Engine
Unreal Engine (UE) is a 3D computer graphics game engine developed by Epic Games, first showcased in the 1998 first-person shooter game '' Unreal''. Initially developed for PC first-person shooters, it has since been used in a variety of genr ...
are currently the two most popular choices for game developers. Although the differences among the different game engines blur as they build their own tools on top of them, different game developers may be too used to a system to change, or attracted by the huge benefits of such engines regardless of pay-walls.
Game middleware
In the broader sense of the term, game engines themselves can be described as middleware. In the context of video games, however, the term "middleware" is often used to refer to subsystems of functionality within a game engine. Some game middleware does only one thing but does it more convincingly or more efficiently than general purpose middleware.
The four most widely used middleware packages
that provide subsystems of functionality include RAD Game Tools' Bink, Firelight FMOD, Havok (software), Havok, and Scaleform GFx. RAD Game Tools develops Bink for basic video rendering, along with Miles audio, and Granny 3D rendering. Firelight FMOD is a low cost robust audio library and toolset. Havok provides a robust physics simulation system, along with a suite of animation and behavior applications. ''Scaleform'' provides GFx for high performance Adobe Flash, Flash UI and high-quality video playback, and an Input Method Editor (IME) add-on for in-game Asian chat support.
Other middleware is used for performance optimisation - for example 'Simplygon' helps to optimise and generate Level of detail (computer graphics), level of detail meshes, and 'Umbra (3D technology company), Umbra' adds occlusion culling optimisations to 3d graphics.
Some middleware contains full source code, others just provide an application programming interface, API reference for a compiled binary library (computer science), library. Some middleware programs can be licensed either way, usually for a higher fee for full source code.
See also
* List of game engines
* List of first-person shooter engines
* List of game middleware
* Game physics
*
3D computer graphics
3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for t ...
* Virtual studio
* Authoring system
References
{{Authority control
Video game development
Video game engines,