The focus of this category is on free and open-source (FOSS) video game software.
Free and open source software is an umbrella term used to describe software that is both free software and open-source software. Games that can be downloaded or played online without payment of a fee are not necessarily free and open source.
The term "free" does not refer to the monetary cost of the software, but to the freedom that the user has to do with it as he pleases. The definition of free software, adopted by the Free Software Foundation, defines free software as a matter of liberty rather than price, although they are generally free of cost too. To be considered free software, according to the policies of the FSF and the GNU Project, the software must be so licensed as to grant the user the freedom to run the program as he wishes, to study how the program works, to change it so that it does what the user wants it to do, to redistribute copies to others, and to distribute copies of modified version to others, allowing others to benefit from any changes that are made to it. In order to accomplish these things, access to the source code is necessary.
Computer programs and applications are made up of source codes that are made by programmers. What a user sees or is able to do while running a program are representations of the codes that make up the program. Software that you purchase, or which may have come preinstalled on your computer, do not come with the source codes, and you do not have permission to view or modify these codes. When you install an application on your computer, it installs a lot of files, but none of these files contain the source code.
Computer programs that come with the source code, or for which the source code is available, are known as open-source programs. Both the compiled programs and the source code are distributed freely to users without a fixed fee. Users of open-source software can do pretty much whatever they want with open source software, although various open-source licenses do place some restrictions.
When a game developer writes the code for a video game, compiles it into an executable program, and distributes it along with the source code, he gives permission to others to access everything about the program. Anyone who downloads the program can play the game, view the source code, modify it, compile it, and then redistribute the modified version of the game. However, open-source license requirements might require that the original programmer be credited for his work, have access to the modified version of the source code, and that the modified game not be sold as proprietary software.
If the original game developer approves of changes made to his code, he might elect to include these changes in the next version of the game, acknowledging the user who modified it as a contributor. In game programming communities, the free and open-source model allows others to contribute to the future development of the game. If the original developer chooses not to adopt the modification, the person who suggested the modification is free to make his own version of the game.
Free software and open source software share the same advocacy, and the differences are subtle. They are not synonymous terms, however. Both free software and open source software include the source code.
Free software allows users to do whatever they want with a program. They can modify and redistribute the source code without the consent of the original game developer, and without even a requirement to communicate with the person or organization that developed the original code. Users of free software can use the source code as the base code of a new project he is working on.
The idea of open source game development is one of a group of people working on a single open source project with the goal of improving upon it. For this reason, many open source projects are developed through non-profit organizations established for that purpose.
Open source games are released under a license in which the copyright holder grants users the right to study, modify, and change the software to anyone. There are various license models available for open source, each with its own terms and conditions. Common licensing models include the Apache License, Mozilla Public License, BSD License, GNU Lesser General Public License, and General Public Licenses in various versions.
The Free Software Foundation prefers a method known as copyleft licensing, which refers to the practice of offering people the right to freely distribute copies and modified versions of the game with a stipulation that the same rights be preserved in derivative works.
Games that are distributed both free and open source are appropriate for this category, as are websites that discuss free and open source game development or licensing.
Recommended Resources
The cross-platform game is playable on FreeBSD, OpenBSD, Linux, macOS, and Windows. Under development by Wildfire Games, the game is free and open-source, using the GPLv2 license for the game engine and CC BY-SA for the game art. In the real-time strategy game, players begin as the leader of an ancient civilization and must gather the resources necessary to raise a military force and defeat enemies. A project overview, game manual, and support forum are featured.
https://play0ad.com/
The Advance Projects allows users to play arcade games with video hardware like televisions, arcade monitors, PC monitors, and LCD screen, running in GNU/Linux, Mac OS X, Windows, and DOS. The collection includes AdvanceMAME, AdvanceMENU, AdvanceSCAN, and AdvanceCOMP. The sources of AdvanceMAME are released under the GPL 2 license, while the included MAME source used for the emulation is released under the MAME 0.106 license. Documentation is provided.
http://www.advancemame.it/
Originally released as CodeRED: Alien Arena by COR Entertainment in 2004, Alien Arena’s game content is proprietary freeware, which prohibits commercial resale, but the CRX engine is open-source. In 2012, an online version became available; through the installation of a small plugin, Windows users can play the game in any browser on the Windows OS. The game combines elements of an old school deathmatch with modern features and has been compared to Quake III.
http://red.planetarena.org/
Based on the Cube engine, AssaultCube is a free, multiplayer, first-person shooter game, with a built-in map editor to help players create their own maps, even allowing for cooperative edit mode in realtime with other players. The source code is available under a ZLIB-like open-source license. The game runs on most major operating systems, such as Apple Mac OS X, Linux, and Microsoft Windows. Screenshots from the game are displayed and a game forum is available.
https://assault.cubers.net/
Cube is an open-source multiplayer and single-player first-person shooter game that supports Windows, Linux, macOS, and BSD. Both the game files and source code can be downloaded from the site. Allowing in-engine editing of geometry in full 3D. Screenshots, documentation, and a support wiki are presented, along with a FAQ and a support forum, which requires the creation of an account. General information about the game and its development is put forth.
http://cubeengine.com/
The free, open-source, multiplayer and single-player first-person shooter game is the successor of the Cube FPS. Supported by Windows, Linux, and macOS, the game is released under a ZLIB open-source license. Game files can be downloaded from the site. Other resources include screenshots, full documentation, an informational wiki, game and engine features, and links to related sites, a FAQ page, and a support forum, which requires registration.
http://sauerbraten.org/
Supporting the Windows, Mac OS X, and Linux platforms, DreamChess is an open-source chess game featuring 3D OpenGL graphics, and providing various chess board sets, ranging from wooden chess pieces to flat figurines. The chess engine, Dreamer, is included, but another XBoard-compatible chess engine, such as Crafty or GNU Chess, can be substituted. Game screenshots are provided, and the program files and source code may be downloaded from the site.
https://www.dreamchess.org/
Freeciv is a free and open-source empire-building strategy game inspired by Civilization, and the history of human civilization. Gameplay begins in prehistory, and the player's mission is to lead a tribe from the Stone Age to the Space Age. The game may be played online against the Freeciv AI as a single-player game or as a multiplayer game, against both human and AI players, online, by email, or in a one-turn-per-day game.
https://www.freecivweb.org/
The project seeks to create open content for the open-source software Doom game engine, which was released by ID Software under the GNU General Public License in 1997. The game is available in two versions, a single-player focused game, split into two parts, each of which is compatible with different versions of the classic Doom, and a multi-focused game for a deathmatch game mode. The program requires the additional download of a game engine, which may also be downloaded free.
https://freedoom.github.io/
A clone of the 1985 Commodore 62 game, Paradroid, the game inherits the theme of fighting hostile robots, the takeover game, and the robot models, its objective being to destroy all of the enemy robots either by shooting them or taking control of them. The final version of the game was released in 2003, supporting the Linux, Mac OSX, Sharp Zaurus, and Windows operating systems. Although FreedroidRPG is the focus, Freedroid Classic may also be downloaded from the site.
http://www.freedroid.org/
Made to be played as a single-player game, with any possible combination of human-computer teams, or over the Internet with Ysagoon Online Gaming, Globulation 2 is a real-time strategy game that automatically assigns tasks to units, allowing players to manage more units, and to focus on strategy rather than micromanagement. Linux, Mac OS, and Windows packages may be downloaded, as well as the source code. Older releases are also available. A user manual and support forum are included.
https://globulation2.org/
Created by Andreas Umbach and released under the GNU General Public License, GLtron, the game supports the Linux, Win32, and MacOS X platforms. Program files and the source code may be downloaded from the site, which also includes a development diary, screenshots, and documentation. Other resources include developer information, plans, and possible improvements in the game, announcements, and answers to frequently asked questions.
http://www.gltron.org/
The game is a free version of a popular game known as Bejeweled or Diamond Mine and is a puzzle game with gems. Developed by Daniele Napolitano, Ivo Reumkens, and their game development community, the game can be installed on Ubuntu, Fedora, Debian, and Arch Linux, and is included in recent releases of openSUSE. The software and the source code are available for download. Development and project documentation, announcements, and code data are available.
http://gweled.org/
The free and open-source cross-platform Sudoku game can be run on any operating system that includes a Java runtime environment (JRE). Licensed under a Creative Commons Attribution License, the game can be freely downloaded. Documentation, support information, and reviews are published to the site, and a discussion area is included. The game allows users to create random Sudoku grids or design their own to play or solve. There are three difficulty levels of play.
http://playsudoku.sourceforge.net/
Originally released with ASCII graphics in 1987, the open-source video game is an evolution of the earlier game, Hack, which was itself a clone of Rogue. Released under the NetHack General Public License, free sharing and modification of the source code is allowed. Within the game, players choose a character race and class for the primary mission of retrieving the Amulet of Yendor in a randomly generated virtual dungeon. Windows and MacOS X binaries are available.
https://www.nethack.org/
Created in 2003, Neverball is a 3D platform game similar to Super Monkey Ball. Available for the Microsoft Windows and Mac OS X platforms, the game is released as free software under the GNU General Public License. Screenshots, credits, and release information are presented, and online support and discussion forum feature technical support, developer discussions, game ideas and suggestions, and other discussions related to the game, and a free chat area.
https://neverball.org/
Serving as a directory of open-source alternatives to classic video games. For each, the original game is listed, with a link to its Wikipedia page. Beneath that, open-source clones are listed, with indications as to whether it is a clone, a similar game, or a tool that is not a game, but something intended to assist in playing or making modifications to the game. Also indicated is whether the game is playable, complete, active, or whether production has been halted, and other information.
https://osgameclones.com/
Licensed under GNU General Public License version 2.0, Pocket Sudoku is a Sudoku application for Pocket PC, currently known as Windows Mobile. The game can generate Sudoku puzzles using six levels of difficulty, solve any valid puzzle, show pencil marks, and give hints when the player gets stuck. Available in several languages, it may be freely downloaded. Project samples, activity reports, documentation, and support information are available.
https://sourceforge.net/projects/pocketsudoku/
Available for Windows, GNU/Linux, BSD, and macOS, Red Eclipse is a free and open-source game built on Cube Engine 2, using SDL and OpenGL. The game is a first-person arena shooter, featuring parkour, impulse boosts, and other features. Game files may be downloaded from the site, and installation instructions are given, along with documentation, discussions, and statistics. Those interested in helping to evolve the game or to contribute financially are welcomed.
https://www.redeclipse.net/
Robocode is a programming game in which the goal is to develop a robot battle tank to battle against other tanks in Java or .NET, in real-time and on-screen. An overview of the software is presented, along with details of the different versions. The software may be downloaded from the site, along with the Java API, .NET API, and .NET Control API. Tutorials on creating a Java robot and a .NET robot with Visual Studio are featured, and a discussion forum is available for technical issues.
https://robocode.sourceforge.io/
Blokish is an open-source clone of Blokus, a four-player board game in which players attempt to place as many of their twenty-one pieces on the board as they can while preventing other players from doing the same. Written by Dan Alcantara in C++, and using wxWidgets and OpenGL, the game utilizes a rudimentary artificial intelligence code. Licensed under a GNU General Public License, the game and source code can be downloaded from the site.
https://sourceforge.net/projects/blokish/
Released under a GNU General Public License 2.0 (GPLv2), Gillo is a two-player desktop video game written in C++, using OpenGL, SDL, and Plib. Set in a 3D ellipsoid playground, players are represented as cars with a magnetic director, able to attract or reject a ball in order to throw it through a goal that is placed in the center of the playing field. Screenshots of the game are displayed, project members are named, and the latest version can be downloaded from the site.
https://sourceforge.net/projects/gillo/
The web-based version of the board game, Settlers of Catan, is written in Java. Created as an AI research project, the client-server system supports multiple simultaneous games between people and computer-controlled opponents. Project samples are displayed as screenshots, project activity is reported, and the game files and source code are available under GNU General Public License version 2.0 (GPLv2). Discussions, feature requests, and patches are featured.
https://sourceforge.net/projects/jsettlers/
SourceForge: Orbit Reconstruction, Simulation and Analysis
Created in 2001, the ORSA project now collects several general classes, a graphical interface running under Linux/Unix, Mac OS X, and Windows, as well as a number of tutorial programs. Written and maintained by Pasquale Tricarico, ORSA is free software and may be downloaded from the site and modified. Game screenshots, documentation, development data, and support information are provided. Links to related sites, such as Orbit integration software and Orbit determination software, are included.
http://orsa.sourceforge.net/
SourceForge: PyPong - Python Pong
Written in Python, built with PyGame, and compiled with cx_freeze, PyPong was created to be just like the original Atari arcade game, except that it runs on any computer supported by Python and PyGame, and is fully customizable. The game files and source code may be downloaded, along with documentation, under an Academic Free License (AFL). Other resources include development notes, project trackers, and forum discussion.
https://sourceforge.net/projects/pythonpong/
Coded in Java, the game was designed to work in both the Linux and Windows platforms. The game features the famous London police agency. Within the game, the moves by the character known as Mr. X are controlled by the program, while the human player’s character is the detective. The game features an enhanced GUI with the detective positions shown on the map. Project samples are shown in screenshots, and the program is licensed under GNU General Public License version 2.0.
https://sourceforge.net/projects/scotland-yard/
SourceForge: The Open Racing Car Simulator
TORCS is a portable multi-platform car racing simulation, which can be used as an ordinary car racing game, as an artificial intelligence racing game, or as a research platform. The simulation runs on all Linux architectures, FreeBSD, OpenSolaris, and Windows. Licensed under the open-source General Public License, the game files and source code may be downloaded from the site, and screenshots, documentation, credits, and video tutorials are available.
http://torcs.sourceforge.net/
Created by Steve and Oliver Baker, the open-source software is released under the GNU General Public License and may be freely downloaded, although it currently is supported only by the Linux operating system. Essentially, a racing game, players always play as Tux, while the computer operates the other drivers. Game screenshots are displayed, and the requirements for installing or playing the game are provided, along with installation instructions and support data.
http://tuxkart.sourceforge.net/
Programmed in Microsoft Visual Basic .NET, Yahtzo! is a Yahtzee! game for computers running the Windows operating system, although the Microsoft .NET Framework needs to be installed on the computer in order to play the game. Released under the GNU General Public License, the game files may be freely downloaded from the site. Project information is set forth, along with answers to frequently asked questions, contact information, and release notes.
http://yahtzo.sourceforge.net/
The Java multi-agent game is a web version of the board game, where one player can battle against the computer using his armies of pieces, the object being to capture the enemy flag by moving pieces toward the enemy while capturing enemy pieces, the goal being to recreate the board game for the computer. Licensed under the GNU General Public License, the game can be freely downloaded. Project announcements, discussions, documents, and files are featured.
http://stratego.tigris.org/
Based on a modified Quake II engine, licensed under the GNU General Public License, the game is free and open-source software. The strategy video game runs on AmigaOS, FreeBSD, Linux, Mac OS X, OpenBSD, and Microsoft Windows, there is also a version for Android mobile devices. UFO: AI can be played in Geoscape mode or in Tactical mode, the former dealing with base management and strategy, while the player takes command of a team of soldiers in the latter.
https://ufoai.org/
The cross-platform, open-source, driving simulation was created with drift racing in mind. Released under the GNU General Public License v.2, the game is available for FreeBSD, Linux, Mac OS X, and Windows operating systems. The game features simulation-grade driving physics, tracks and cars based on real-world tracks and cars, competition against AI players, and support for joysticks, gamepads, wheels, or keyboards. The programs files and source code may be downloaded.
http://vdrift.net/
Inspired by Settlers II, Widelands is a free, open-source, real-time strategy game that supports single-player campaigns and a multiplayer mode. Each player in the game is a regent of a small clan, although they start out with nothing but a headquarters, where all of the clan’s resources are stored. The initial objective is to expand the headquarters into a settlement. Players interact with other players by trading or fighting with them. Game files and the source code may be downloaded.
https://www.widelands.org/
