Game programming, a subset of game development, is the software development of video games. Game programming requires substantial skills in software engineering, computer programming in a given language, and expertise in one or more following area: simulation, computer graphics, artificial intelligence, physics, audio programming, and input. For multiplayer games, knowledge of network programming is required (the resultant code, in addition to its performance characteristics, is commonly referred to as the game's netcode by players and programmers alike). In some genres, e.g., fighting games, advanced network programming is often demanded, as the netcode and its properties (e.g., latency) are considered by players and critics to be some of the most important metrics of the game's quality. For massively multiplayer online games (MMOGs), even further knowledge of database programming and advanced networking programming are required. Though often engaged in by professional game programmers, there is a thriving scene of independent developers who lack a relationship with a publishing company.

Development process Professional game development usually begins with a game design, which itself has several possible origins. Occasionally the game development process starts with no clear design in mind, but as a series of experiments. For example, game designer Will Wright began development of The Sims by getting programmers to experiment with several ideas.

Prototyping Programmers are often required to produce prototypes of gameplay ideas and features. A great deal of prototyping may take place during pre-production, before the design document is complete, and may help determine what features the design specifies.

Prototypes are developed quickly with very little time for up-front design and mostly act as a proof of concept or to test ideas. They are not expected to work flawlessly, but are developed to try out new, sometimes exotic, ideas.

Game design

Though the programmer's main job is not to develop the game design, the programmers often contribute to the design, as do game artists. The game designer will solicit input from both the producer and the art and programming lead for ideas and strategies for the game design. Often individuals in non-lead positions also contribute, such as copywriters and other programmers and artists.

Programmers often closely follow the game design document. As the game development progresses, the design document changes as programming limits and new abilities are discovered and exploited.

Production During production, programmers may create a great deal of source code to create the game described in the game's design document. Along the way, the design document is modified to meet limits or expanded to exploit new features. The design document is very much a "living document", much of whose life is dictated by programmer's schedules, talent and resourcefulness.

While many programmers have some say in a game's content, most game producers solicit input from the lead programmer as to the status of a game programming development. The lead is responsible for knowing the status of all facets of the game's programming and for identifying limits. The lead programmer may also pass on suggestions from the programmers as to possible features they'd like to implement.

With today's visually rich content, the programmer must often interact with the art staff. This very much depends on the programmer's role, of course. For example, a 3D graphics programmer may need to work with the game's 3D modelers discussing strategies and design considerations, while an AI programmer may need to interact very little, if at all, with the art staff. To help artists and level designers with their tasks, programmers may volunteer or be called on to develop tools and utilities. Many of these may be for a specific purpose and can be buggy due to time constraints (time for development of such tools is often not included in a game's schedule) as well as because they are only for in-house use anyway. Many game tools are developed in rapid application development (RAD) languages for quicker development and may be discarded after the completion of the game.

Testing

The formal quality assurance testing process, performed by professional game testers, begins well into game development. High-budget titles may begin testing with the first playable alpha, while low-budget and casual games might not enter testing until a release candidate is ready. The programmers' task is to fix errors and bugs as such are discovered by the QA teams.

Nearing completion Final tasks include "polishing" the game, such as programmers fixing occasional bugs—from minor to catastrophic—that may arise during the last phases of testing.

Game developers may have a beta testing period, but the definition of such varies from developer to developer. Often a beta contains all of the game's features, but may have a few bugs or incomplete content. Few games are given a public beta period, for example, to measure stress tolerance for game servers.

When the game is deemed complete, it is said to have "gone gold" and is shipped off to the publisher. Depending on circumstances, the publisher may then subject it to its own quality assurance or may begin pressing the game from the gold master.

Maintenance Once a game ships, the maintenance phase for the video game begins. Programmers wait for a period to get as many bug reports as possible. Once the developer thinks they've obtained enough feedback, the programmers start working on a patch. The patch may take weeks or months to develop, but it's intended to fix most bugs and problems with the game. Occasionally a patch may include extra features or content or may even alter gameplay.

Duration Most modern games take from one to three years to complete. The length of development depends on a number of factors, but programming is required throughout all phases of development except the very early stages of game design.

Tools Like other software, game development programs are generated from source code to the actual program (called the executable) by a compiler. Source code can be developed with almost any text editor, but many professional game programmers use a full integrated development environment. Once again, which IDE one uses depends on the target platform.

In addition to IDEs, many game development companies create custom tools developed to be used in-house. Some of these include prototypes and asset conversion tools (programs that change artwork, for example, into the game's custom format). Some custom tools may even be delivered with the game, such as a level editor.

Game development companies often invest in high-quality equipment and multiple systems to support their programming staff. A standard workstation often includes two to three development systems and multiple monitors in their office or cubicle.

Programming languages Language Features Assembly Potentially minimal CPU overhead C Widely known, widely portable, many APIs, compiles to machine code C++ Object-oriented, widely known, many APIs, compiles to machine code Java Object-oriented, garbage-collected, widely portable (via a virtual machine) C#, Visual Basic (.NET), etc. Object-oriented, garbage-collected, interfaces with Microsoft products Objective-C, Swift Object-oriented, interfaces with Apple products Lua, Python, JavaScript, Tcl, etc. Familiar syntax, easily embedded in the above languages, often used for scripting Lisp, Pascal, Perl, Smalltalk, etc. Fringe game languages, although bindings to popular libraries are common Once the game's initial design has been agreed on, the development language must be decided on. The choice depends on many factors, such as language familiarity of the programming staff, target platforms, execution speed needs, the language of any game engines, application programming interfaces (APIs), and libraries being used.

For personal computers, the language selected may be little more than a matter of preference. Language bindings for popular libraries such as Simple DirectMedia Layer (SDL) and Allegro are widespread, and the performance gap between idiomatic code written in modern compiled languages is negligible. The most popular languages are usually procedural or object-oriented and implemented via compilers; for example, C, C++, and Java. However, developers may take into account domain-specific features, such as interfacing with the operating system, and resilience to reverse engineering for online video games. Many games are not written in one language exclusively, and may combine two or more languages; For example, Unity, a popular game engine, has different pieces written in C, C++, and C#.

For consoles, the support of the target platform is usually the most considered factor. In the past, video games for consoles were written almost exclusively in assembly due to limited resources in terms of both storage and processing speed. However, as technology has advanced, so have the options for game development on consoles. Nintendo, Microsoft, and Sony all have differing software development kits (SDKs) for their Nintendo Switch, Xbox One, and PlayStation 4 consoles, respectively.

High-level scripting languages are increasingly being used as embedded extensions to the underlying game written in a compiled programming language, for the convenience of both the original developer and anyone who would wish to mod the game. Lua is a very popular choice, as its API is written in ANSI C and the language is designed to be embedded into other applications. Many developers have created custom languages altogether for their games, such as id Software's QuakeC and Epic Games' UnrealScript.

APIs and libraries A key decision in game programming is which, if any, APIs and libraries to use. Today, many libraries exist which handle key tasks of game programming. Some libraries can handle sound processing, input, and graphics rendering. Some can even handle some artificial intelligence (AI) tasks such as pathfinding. There are even entire game engines that handle most of the tasks of game programming and only require coding game logic.

Which APIs and libraries one chooses depends largely on the target platform. For example, libraries for PlayStation 2 development may not be available for Microsoft Windows and vice versa. However, there are game frameworks available that allow or ease cross-platform development, so programmers can program a game in one language and have the game run on several platforms, such as the Wii, PlayStation 3, Xbox 360, PSP and Microsoft Windows.

Graphic APIs +Graphics API use across operating systemsOSVulkanDirect XGNMXMetalWindows 10 MacLinuxAndroidiOSTizenSailfishXbox OneOrbis OS (PS4)Nintendo Switch Today, graphics are a key defining feature of most games. While 2D graphics used to be the norm for games released through the mid-1990s, most AAA games now boast full 3D graphics, even for games which are largely 2D in nature, such as Civilization III. However, purely 2D graphics have experienced a Renaissance with indie games.

The two most popular 3D graphics APIs for Microsoft Windows are Direct3D and OpenGL. The benefits and weaknesses of each API are hotly debated among Windows video game programmers.

Currently, the most popular Computing platform is Google Android. Since it comes pre-installed on almost eighty percent of Smartphones sold, Android has the second largest user base, and increasing. Android uses OpenGL ES & Vulkan (API).