An unofficial patch, a.k.a. community patch and fan patch, is a software update created by a third party, such as a user community, without the involvement of whoever is considered the official maintainer of the software (i.e. original developer). An unofficial patch generally does not change the intended use of the software, in contrast to other third-party adaptions such as mods or cracks.

An unofficial patch is typically intended to repair bugs and provide new capabilities such as support for newer operating systems, increased display resolutions and new display formats. While unofficial patches are most common for the PC platform, they can also be found for console games e.g. in context of the emulation community.

A fan translation is an unofficial patch that adds natural language support to software. Fan translations are most common for Japanese role-playing games which are often not localized for Western markets.

A slipstream like patch combines multiple official patches into one unofficial update package as a convenience to users when individual patches are only available online or as small incremental updates.

A common motivation for creating an unofficial patch is lack of technical support from the official maintainer which may result from:

  • The software reached the maintainer's defined end-of-life
  • The software was superseded by a successor product
  • The software was originally designed to operate in a substantially different environment and may require improvement/optimization
  • The maintainer went out of business
  • Support is not economically viable (e.g. localization for small markets)
  • A fast solution for a time critical problem (e.g. security holes) when an official one takes too long
  • The official maintainer is unable to cope with the problems

Methods

The most common case is that the source code and the original development tools are not available for the software. Therefore, the faulty software's binary must be analyzed at run time by reverse engineering and debugging. If the problem is found, a fix to the program must be applied. Sometimes only small changes in configuration files or the registry are required, sometimes binary hacks on the executable itself are required to fix bugs. If a software development kit (e.g. for modding) is available, fixes to the content can be easily produced, otherwise the community would need to create their own tools. These found fixes are typically packed to user deployable patches (e.g. with NSIS, Innosetup).

If the source code is available, support can by provided most effectively. Sometimes the source code is released intentionally, sometimes by leaking or mistake, such as what happened with the game engine of the Thief series. Sometimes fans even completely reverse-engineer source code from the original program binary. With the source code available even the support of completely different but recent platforms with source ports becomes possible.

Law

While no court cases have directly addressed the legal ramifications of unofficial patches, similar cases have been tried on related issues. The case of Galoob v. Nintendo found that it was not copyright infringement by a user to apply an unauthorized patch to a system (while the scope was very specific to the Game Genie). On the other hand, the case Micro Star v. FormGen Inc. found that user-generated maps were derivative works of the original game. In Sega v. Accolade, the 9th Circuit held that making copies in the course of reverse engineering is a fair use, when it is the only way to get access to the "ideas and functional elements" in the copyrighted code, and when "there is a legitimate reason for seeking such access". According to Copyright law of the United States 17 U.S. Code § 117, the owner of a copy of a program can modify it as necessary for "Maintenance or Repair", without permission from the copyright holder; an argumentation also raised by Daniel J. Bernstein professor at the University of Illinois at Chicago.

Similar user rights are given also according to European copyright laws. The question of whether unauthorized changes of lawfully obtained copyright-protected software qualify as fair use is an unsettled area of law. An article of Helbraun law firm remarks, in the context of fan translations, that while redistributing complete games with adaptions most likely does not fall under fair use, distributing the modifications as a patch might be legally permissible; however, that conclusion has not been tested in court.

Reception

Reception of unofficial patches is mixed, but by large, copyright holders are ambivalent. When the software is not considered commercially viable unofficial patches are ignored by the copyright holder as it is not seen as a source of lost revenue. There have been seldom cases of cease and desist letters to unofficial patch and fan translation projects.

Sometimes the copyright holder actively support the patching and fixing efforts of a software community, sometimes even by releasing the source code under a software license which allows the software community the continued software support by themselves. Examples for such software are in the List of commercial video games with later released source code.

The free and open source software movement was founded in the 1980s to solve the underlying problem of unofficial patches, the limited possibility for user self-support in binary only distributed software due to missing source code. Free and open source software demands from distributed software the availability of source code, which prevents the technical problems and legal uncertainties of binary only user patching of proprietary software.

Examples in video games

Computer gameType
AnachronoxBug fix patch
Age of Empires: The Rise of RomeBug fixes, balance fixes, stability fixes, UI and sound improvements, resolution fixes including support for more higher definition resolutions
Arcanum: Of Steamworks and Magick ObscuraBug fix patch, fan translation
Battlezone IIBug fix patch
Civilization IVBug fixes and extensions, (with SDK source code and accessible XML configuration and Python files)
Civilization VBug fixes and extensions (based on source code)
Chrono TriggerFan translation, bug fix patch
Command & ConquerBug fix patch, resolution fixes, added support for language packs
Dark Souls IIBug fixes
Deadly Premonition: The Director's CutResolution fix
Ecco the DolphinBug fixes, ports for newer OSes
The Elder Scrolls II: DaggerfallBug fix patch, fan translation
The Elder Scrolls V: SkyrimBug fix patch, translation fixes
Empire Earth 2Bug fixes, unhandled exception crash fixes, Windows 8 / 10 / 11 support, more screen resolutions (including 4k and the custom screen resolution generator), DirectX 9 support, G-Sync / FreeSync and high monitor refresh rate fixes, unlimited camera zoom settings, changed low-quality sounds, new options in game (e.g. more population, cycle time of day, disable crowns system and leaders), integrated language changer, integrated private multiplayer server and many more new features (fully customizable), frequently updated.
E.T. the Extra-TerrestrialBug fixes
Fallout 2Bug fixes, resolution fixes
Fallout: New VegasBug fixes, stability and performance fixes (especially for modern systems)
Fallout 4Bug fixes
FreelancerBug fix patch
Grand Theft Auto: San AndreasEngine, graphics and quality-of-life fixes
Gothic 3Bug fix patch
Infinity Engine (Baldur's Gate series, Icewind Dale etc.)Bug fix patch, resolution fixes
IL-2 Sturmovik: Cliffs of DoverFix mod based on source code (which later became an official release as "Blitz Edition")
Jagged Alliance 2 (now JA2-Stracciatella)Bug fix patch, resolution fixes, ports
Jazz Jackrabbit 2Bug fixes, stability fixes, new features for client side and server side
Legacy of Kain seriesBug fix patch
LucasArts adventures (Monkey Island, Indiana Jones, etc.)Fan translation
Master of MagicFan patch
Master of Orion 3Fan translation, bug fix
MinecraftFan fixes implemented to latest patches
MVP Baseball 2005Fixes, support continuation
Nier: AutomataResolution fixes, performance fix
Nuclear ThroneVarious bug-fixes for co-op mode, as well as addition of online co-op
ParadroidBug fixes, speed fixes
RollcageBug fix patch
Silent Hill 2'Enhanced Edition' rehaul, including bug fixes, enhanced and remade graphic assets, full widescreen support, HD cutscenes, and numerous modern improvements
Silent Hunter II / Destroyer CommandBug fix patch (Ubisoft endorsed with source code)
Star OceanFan translation
Star Wars: Knights of the Old Republic II – The Sith LordsBug fixes, restored content, widescreen support
Supreme CommanderBug fixes, multiplayer client and server replacement (Server emulator)
Dark Engine (Thief 1, Thief 2, System Shock 2)Bug fix patch
Titan QuestBug fix patch
Ultima seriesBug fix patch, fan translation
Ultima 4Bug fix patch, remaster
Vampire: The Masquerade – BloodlinesBug fix patch, restored content, widescreen and modern OS support
XenonautsBug fix patch and support continuation

Examples in general software

SoftwareType
3dfx driversDriver fixes, continued support
Adobe AcrobatFast security fix
Socket 7 boards' Award BIOS32 GB+ HDD support, AMD K6-2/3+ support
iOS 4.3.3Fast security fix
JavaFast security fix
Windows 7, Windows 8Unlocking of hardware support
Windows 98Slipstream patch, Bug fix patch, support for harddrives > 137 GB, support for 2k API
Windows XPUpdate pack
Internet ExplorerFast security fix
Nvidia nForce Chipset Device driverSupport for older Chipsets on newer Windows OSs
Palm PreFunctionality extension
Windows Metafile formatFast security fix
Windows URI problemFast security fix
Mac OS X 10.3Daylight saving time patch

See also