List of commercial video games with available source code

Motivation

Commercial video games are typically developed as proprietary closed source software products, with the source code treated as a trade secret (unlike open-source video games). When no more revenue is expected, these games may enter their end-of-life as a product with no support or availability for the game's users and community, becoming abandonware.

Description

In several of the cases listed here, the game's developers released the source code expressly to prevent their work from becoming abandonware. Such source code is often released under varying (free and non-free, commercial and non-commercial) software licenses to the games' communities or the public; artwork and data are often released under a different license than the source code, as the copyright situation is different or more complicated. The source code may be pushed by the developers to public repositories (e.g. Sourceforge or GitHub), or given to selected game community members, or sold with the game, or become available by other means. The game may be written in an interpreted language such as BASIC or Python, and distributed as raw source code without being compiled; early software was often distributed in text form, as in the book BASIC Computer Games. In some cases when a game's source code is not available by other means, the game's community "reconstructs" source code from compiled binary files through time-demanding reverse engineering techniques. Source code availability in whatever form allows the games' communities to study how the game works, make modifications, and provide technical support themselves when the official support has ended, e.g. with unofficial patches to fix bugs or source ports to make the game compatible with new platforms.

Games with available source code

The table below with available source code resulted not from correct releases of companies or IP holders but from unclear release situations, like lost & found and leaks of unclear legality (e.g. by an individual developer on end-of-product-life).

Games with restored source code

Once games, or software in general, become an obsolete product for a company, the tools and source code required to re-create the game are often lost or even actively destroyed and deleted. On the closure of Atari in Sunnyvale, California in 1996, the original source code of several milestones of video game history (like Asteroids or Centipede) were thrown out as trash.

When much time and manual work is invested it is however still possible to recover or restore a source code variant which replicates the program's functions accurately from the binary program. Techniques used here are decompiling, disassembling and reverse engineering the binary executable. This approach typically does not result in the exact original source code but a diverging version as a binary program does not contain all information originally carried in the original source code. Comments and function names cannot be restored if the program was compiled without additional debug information. The here given in "bottom up" development methodology re-created source-code of games is able to replicate the behaviour of the original game exactly, unlike game engine recreations which are often made in top down methodology resulting in general game engines and not accurately representing the original game.