An open-source video game, or simply an open-source game, is a video game whose source code is open-source. They are often freely distributable and sometimes cross-platform compatible.
Definition and differentiation
Not all open-source games are free software; some open-source games contain proprietary non-free content. Open-source games that are free software and contain exclusively free content conform to DFSG, free culture, and open content and are sometimes called free games. Many Linux distributions require for inclusion that the game content is freely redistributable, freeware or commercial restriction clauses are prohibited.
Background
In general, open-source games are developed by relatively small groups of people in their free time, with profit not being the main focus. Many open-source games are volunteer-run projects, and as such, developers of free games are often hobbyists and enthusiasts. The consequence of this is that open-source games often take longer to mature, are less common and often lack the production value of commercial titles. In the 1900s a challenge to build high-quality content for games was the missing availability or the excessive price for tools like 3D modeller or toolsets for level design.
In recent years, this changed and availability of open-source tools like Blender, game engines and libraries drove open source and independent video gaming. FLOSS game engines, like the Godot game engine, as well as libraries, like SDL, are increasingly common in game development, even proprietary ones. Given that game art is not considered software, there is debate about the philosophical or ethical obstacles in selling a game where its art is proprietary but the entire source code is free software.
Some of the open-source game projects are based on formerly proprietary games, whose source code was released as open-source software, while the game content (such as graphics, audio and levels) may or may not be under a free license. Examples include Warzone 2100 (a real-time strategy game) and Micropolis (a city-building simulator based on the SimCity source code). Advantage of such continuation projects is that these games are already "complete" as graphic and audio content is available, and therefore the open-source authors can focus on porting, fixing bugs or modding the games.
In a 2004 article, Adam Geitgey questioned the compatibility of the open-source culture with respect to the game development process. He suggested that perceived open-source development advantages do not work for games because users move on to new games relatively quickly and so do not give back to the project. Geitgey further noted that music and art development is not built up from the work of others in the same way that coding would be. He argued that high quality art content is required, which is typically produced commercially by paid artists. While Linux operates on the open-source philosophy, this may not benefit game development.
As of September 2015, the Steam gaming service has 1,500 games available on Linux, compared to 2,323 games for Mac and 6,500 Windows games.
History
Beginnings and early games
Just as in most other forms of software, free software was an unconscious occurrence during the creation of early computer games, particularly for earlier Unix games. These are mostly arcade conversions, parlour games, and text adventures using libraries like curses. A notable example of this is the "BSD Games", a collection of interactive fiction and other text-mode titles. Game fan communities such as the modding community do include some aspects of free software, such as sharing mods across community sites, sometimes with free to use media made for the modification.