While many software providers choose to vigorously defend their intellectual property rights in the software they create, in the gaming industry, some developers of PC video games have taken a different approach by allowing or even encouraging fans of their games to modify (or mod) them. Fan-developed modifications of video games have been made since the 1980s,¹ usually by fans seeking to enhance or replace visual elements of, add gameplay features or characters to, or fix bugs or errors in a game.² Mods are sometimes released by their creators (or modders) to the gaming community for free, but, in other instances (including some condoned or created by major gaming studios), they may be released for a fee, from behind paywalls, or as entries into contests.³

Game developers have taken divergent approaches to interacting with modders, ranging from aggressively seeking to stop modders' activities,⁴ to utilizing communities of modders to develop and release patches to their games,⁵ to opening up mod marketplaces and releasing free software and tools to facilitate modding.⁶ A recent re-release of the source code of an old game, Command & Conquer: Tiberian Dawn, under the GNU General Public License v3 open source license by major game developer Electronic Arts, is the latest step in a long-emerging trend of studios embracing interactions with their fans and promoting vibrant mod communities.⁷

History of Modding: From Doom to Counter-Strike

Electronic Arts published the Adventure Construction Set, a computer game creation system, in 1984 on the Commodore 64, an 8-bit home computer that was introduced in 1982.⁸ Adventure Construction Set allowed users to construct their own graphical adventure games, which in many ways was a precursor to the map editors that game developers would later package with games to facilitate modding in the form of do-it-yourself game level creation.⁹ As computers became more accessible to consumers throughout the 1980s and early 1990s, so did PC gaming and modding. By 1993, when id Software released Doom, a widely popular first-person shooter game, its fans formed one of the earliest and largest modding communities.¹⁰

The source code underlying Doom was released by id Software in 1997 under a license that allows modding of the game for non-profit use.¹¹ This means that fans of Doom have been able to download, install, and modify the source code underlying Doom for over two decades (so long as they were not seeking to profit from their endeavors). The results have been nothing less than industry shaping. The Doom mod community took a 24-level-long game and added near infinite levels to it; they created alternative versions of Doom that at times outshined the original game and informed future releases of the game, such as Aliens TC and Brutal Doom.¹²

Other modding communities have also been very active. For example, Counter-Strike was released by two modders in 1999 as a mod to Valve Corporation's 1998 game Half-Life, which had been, in turn, created by Valve from its own modification to the game engine from the 1996 game Quake (which Valve licensed from id Software).¹³ Defense of the Ancients (DotA), which was released in 2003, is a mod of Blizzard Entertainment's 2002 game Warcraft III: Reign of Chaos. Both DotA and Counter-Strike began as fan-made, modding-community creations that were initially created and released for free. Both mods were more popular than the original games on which they were based, generated hundreds of millions of dollars in revenue for holders of rights in the games, and spawned lasting eSports communities devoted to these games that persist to this day.

As an increasing number of modified games exceed the popularity of their original titles, game developers, on the other hand, have become increasingly incentivized to take back control over their intellectual property. For example, within one year of Counter-Strike's release, Valve contacted the modders behind it and hired their employer, Barking Dog Studios, to work with Valve on developing games together. DotA, on the other hand, has been the subject of a decade-long dispute between Blizzard and Valve as to which company owns DotA, after Valve paid the modder behind DotA for all rights in the mod that was created using a map editor Blizzard distributed with Warcraft III: Reign of Chaos.¹⁴ When id Software released Doom 2016 in 2016, it did not release (and still has not released) the source code for it despite the vibrant modding community centered around the original Doom.¹⁵

Infringement vs. Fair Use: Which Mods Are Permissible?

Video games are protected under copyright law, and game studios and other developers typically hold copyright and other intellectual property rights in their games. Developers that wish to encourage modding will often grant third parties (or any users of their game) certain permissions to modify their games. In limited circumstances, modders can modify a game without a developer's permission if the mod constitutes a fair use of the game's copyright. In the United States, the question of whether a mod constitutes a fair use of a game's copyright is determined by a court, which looks at the modder's purpose. If the purpose of a mod is criticism, commentary, news reporting, teaching, scholarship, or research, then that mod may be considered a fair use of the original game's copyright, giving the modder a defense against claims that the mod infringes the developer's copyright in the game.¹⁶

If a game developer has not granted permission to modify its game and a modder is unable to rely on the fair use doctrine as a defense for its unauthorized use of the copyrighted work, then it is left to game developers (or publishers with rights to games) to enforce their rights. Game developers and publishers that hold or have been granted rights to games may take defensive or offensive measures to protect their intellectual property rights. A few recent examples of companies taking positions on mods to their games are:

• Early 2020: Blizzard updated its Custom Game Acceptable Use Policy, further clarifying that all mods (which are "Custom Games" under the policy) are its property and must be accessible by all users when distributed by modders.¹⁷
• Late 2019: Take-Two Interactive (Take-Two), as publisher of the Red Dead franchise, sued for copyright infringement the modders behind Red Dead Redemption: Damned Enhancement Project, which included a mod that enabled Red Dead Redemption 1 to run on a PC, when Take-Two had not yet released the game on PC.¹⁸
• Early 2019: Take-Two and Rockstar Games, as publisher of the Grand Theft Auto franchise, sued for copyright infringement the modders behind Evolve, a "cheat menu" mod that enabled players to gain god-like powers that other players did not have.¹⁹

While a mod may constitute a fair use of a game's copyright, whether a game developer or publisher takes action against an infringing modder appears tied to the perception of fairness as well, as it appears that game companies may be more likely to enforce their rights against unauthorized modders if the mod in question is used to facilitate cheating.²⁰

Choosing Open Source: What Are the Options?

If a developer would like to permit fans to modify its games, it can set the tone for the type of mod community it wants to foster. One primary means by which developers can achieve this is by choosing one of many types of open source licenses to govern the source code underlying the game being released for modding.

Open source software is software typically released for free ("free" as in "free speech," not as in "free beer"),²¹ but is made available under license terms that impose certain conditions, restrictions, and obligations on the licensee. These range from requirements to reproduce author attribution and copyright notices when distributed, to the requirement that any modifications or derivatives of the open source software be distributed in source code form under the same free and open license terms.

Open source software licenses generally fall into two categories:

• Permissive licenses, which would broadly authorize modding, so long as modders give credit to the original developer (for example, the Apache 2.0, BSD 3-Clause, BSD 2-Clause, and MIT licenses); and
• Copyleft licenses, which would authorize modding, so long as modders give credit to the original developer and distribute the mod in source code form under open source license terms or the same license terms (for example, the GNU General Public License, the Creative Commons "Share Alike" license, and the Mozilla and Eclipse licenses).

Game developers looking to allow modders to freely commercialize their mods should choose permissive licenses, whereas game developers seeking to encourage modders to share the source code of underlying mods that the modders are commercially benefitting from will generally prefer copyleft licenses. Other game developers may create their own, unique license terms to govern the release of their games (including any released source code) and any mods to them.

Mod Community Engagement and Mod Monetization Strategies

Selecting license terms to govern a released game combines business and legal considerations. Game developers should consider what types of fan bases are likely to form around the games they are developing and how the developer would like to interact with those communities of fans.

A developer creating a PC video game should spend some time determining the parameters of its mod policy. The policy does not have to be overly formal, but at a minimum should cover: 1) whether the developer will release the source code underlying the game to the public or a set of tools that would allow modders to create mods without the source code; 2) what license will govern any source code or tools released by the developer; and 3) whether modders can monetize mods they create. If, for example, the target gamer is a PC gamer, the developer is committed to releasing source code underlying the game and would like to permit modders to own and commercialize their mods (so long as the modders share the source code underlying their mods publicly), then a developer should consider releasing the game's underlying source code under an open source license like GNU General Public License, which is the most common copyleft license.

Having a coherent mod policy in place prior to a game's release can ease a developer's interactions with mod communities that form after the game's release, as modders are timely made aware of what they can and cannot do with a game's source code. A few examples of how different developers have navigated messaging (or not messaging) their mod policies to fan bases are:

• Mod Freely Approach: Electronic Arts' release of Command & Conquer: Tiberian Dawn under the GNU General Public License v3 enables gamers and modders to do what they want with the open-sourced aspects of the game, so long as they give credit to Electronic Arts as the developer and they distribute any mod's source code under the same license. Prior to releasing the game, Electronic Arts engaged active mod communities that had been creating additional versions of the original game for over two decades.²² By taking this approach, Electronic Arts was able to benefit from the mod community's experience with the game and release a game tailored to its most likely users.
• Mod For a Fee Approach: Bethesda Softworks, developer of The Elder Scrolls and Fallout franchises, pays modders through its Creation Club.²³ The Creation Club includes mods from well-known modders in the game's mod communities, who receive compensation from Bethesda for their contributions to the game. By enabling modding in this manner, Bethesda is able to benefit from having programmers fix and improve its games without employing them.
• Selective Enforcement Approach: Some game developers have chosen to not publicly support or expressly allow for the modding of their games, but have provided some de facto support or permission for modding by choosing either to not enforce their rights against modders or to only selectively come after certain modders, such as those that create mods designed to promote cheating or the insertion of inappropriate content into an otherwise age-appropriate game.²⁴
• No Modding Approach: Nintendo is famous for taking aggressive action to defend its intellectual property rights, and Nintendo has historically sent cease-and-desist letters to modders as it becomes aware of the mods. Nintendo's no modding approach is aligned with Japan's approach on modding more generally. The Japanese government recently expanded regulations under its Unfair Competition Prevention Law to make modding game save data and game consoles punishable by up to five years in jail and up to $46,000 in fines.²⁵

Game developers are free to choose their own adventure in developing and releasing games, but how a developer is perceived by fans of its games should not be overlooked. Consistent messaging and soliciting feedback from existing mod communities have proven to be useful strategies to maximize the benefits of modding in some instances, but there is no one-size-fits-all model. It may be difficult to look past the initial goal of making a well-received game, but developers should ask themselves the question: assuming the game is well-received, what should gamers and modders be allowed to do with it?

Please do not hesitate to contact Adam Shevell, Scott McKinney, or Julie Krosnicki for more information on mods and open source software and licenses. For more information about gaming companies generally, please contact any attorney of the firm's electronic gaming practice.

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[1] See Adventure Construction Set, Wiki (last accessed July 12, 2020), https://en.wikipedia.org/wiki/Adventure_Construction_Set; Andi Hamilton, The cult of doom: the thriving mod scene behind id’s classic, PC Gamer (Dec. 10, 2018), https://www.pcgamer.com/the-cult-of-doom-the-thriving-mod-scene-behind-ids-classic/ (initially published in PC Gamer issue 279 in 2015); Mark Kretzschmar & Mel Stanfill, Video Game Modifications between IP Theft and Promotion: Recent Developments, S&LS Blog (Oct. 11, 2019), https://socialandlegalstudies.wordpress.com/2019/10/11/video-game-modifications-between-ip-theft-and-promotion/.

[2] PC Game Mods: What You Need to Run Game Mods, Intel (last accessed July 12, 2020), https://www.intel.com/content/www/us/en/gaming/resources/mods.html.

[3] Greg Finch, The Top 10 Game Mods of All Time, Vice (July 20, 2011), https://www.vice.com/en_us/article/4x45mp/the-top-10-game-mods-of-all-time.

[4] Nintendo’s aggressive approach on taken legal action against modders is no secret. Last year, the creator of a popular mod of Super Mario Bros. called Mario Battle Royale changed the name of the mod to DMCA Royale after the modder received cease-and-desist letters from Nintendo. After changing the name and continuing negotiations with Nintendo, the modder eventually pulled the mod to avoid further legal action. See Ash, [UPDATE] Mario Royale and DMCA Royale are dead, Jim, MS Power User (June 29, 2019), https://mspoweruser.com/dmca-royale-is-dead-jim/; Luke Plunkett, Nintendo’s Lawyers Need to Chill, Kotaku (June 27, 2019), https://www.kotaku.com.au/2019/06/nintendos-lawyers-need-to-chill/.

[5] See, e.g., Steven Hansen, Fan mod aims to ‘eventually fix every bug with Fallout 4,’ Destructoid (Apr. 25, 2016), https://www.destructoid.com/fan-mod-aims-to-eventually-fix-every-bug-with-fallout-4--357612.phtml.

[6] Credited as the “best and largest source of mods,” the Steam Community Workshop piggybacks off of Steam’s user base; Steam is a very popular digital game store with over 100 million active users. Rafi Letzter, Online communities are changing video games to make them better, weirder, and much more wonderful, Business Insider (July 20, 2015), https://www.businessinsider.com/video-game-modding-2015-7; Steam Community Workshop: Create, discover, and download content for your game, Steam (last accessed July 13, 2020), https://steamcommunity.com/workshop/.

[7] /u/EA_Jimtern, Remaster Update and Open Source / Mod Support, Reddit: /r/commandandconquer (May 20, 2020), https://www.reddit.com/r/commandandconquer/comments/gnevp8/remaster_update_and_open_source_mod_support/fr97x9x/; Michael Kan, EA to Open Source PC Game Command & Conquer, Enabling You to Create Crazy Mods, PC Mag (May 20, 2020), https://www.pcmag.com/news/ea-to-open-source-pc-game-command-conquer-enabling-you-to-create-crazy.

[8] Greg Finch, The Top 10 Game Mods of All Time, Vice (July 20, 2011), https://www.vice.com/en_us/article/4x45mp/the-top-10-game-mods-of-all-time. See also Adventure Construction Set, Wiki (last accessed July 12, 2020), https://en.wikipedia.org/wiki/Adventure_Construction_Set.

[9] The Commodore 64 sold from 1982 through 1992 and is credited as being the best-selling computer in history. Ian Matthews, Commodore 64 – The Best Selling Computer in History, Commodore Computers (May 19, 2003; revised Feb. 1, 2020), https://www.commodore.ca/commodore-products/commodore-64-the-best-selling-computer-in-history/.

[10] Andi Hamilton, The cult of doom: the thriving mod scene behind id’s classic, PC Gamer (Dec. 10, 2018), https://www.pcgamer.com/the-cult-of-doom-the-thriving-mod-scene-behind-ids-classic/ (initially published in PC Gamer issue 279 in 2015).

[11] id Software / Doom, The DOOM sources as originally released on December 23, 1997, GitHub (committed on Jan. 31, 2012), https://github.com/id-Software/DOOM/commit/4eb368a960647c8cc82d721d0183629ae10759d1.

[12] Matthew Gault, ‘Doom’ Will Never Be Eternal Without Mods, Vice (Jan. 21, 2020), https://www.vice.com/en_us/article/5dmg8b/doom-will-never-be-eternal-without-mods.

[13] Mark Kretzschmar & Mel Stanfill, Video Game Modifications between IP Theft and Promotion: Recent Developments, S&LS Blog (Oct. 11, 2019), https://socialandlegalstudies.wordpress.com/2019/10/11/video-game-modifications-between-ip-theft-and-promotion/.

[14] Kyle Orland, Blizzard now claims full copyright for player-made “custom game” mods, Ars Technica (Jan. 29, 2020), https://arstechnica.com/gaming/2020/01/blizzard-now-claims-full-copyright-for-player-made-custom-game-mods/; Alissa McAloon, Valve’s ownership of Dota 2 is set to be decided by a jury, Gamasutra (May 22, 2017), https://www.gamasutra.com/view/news/298542/Valves_ownership_of_Dota_2_is_set_to_be_decided_by_a_jury.php.

[15] Id Software, GitHub (last accessed July 12, 2020), https://github.com/id-Software. See also crazyflyingdonut, Open-sourcing Doom 2016 may not happen…, DoomWorld (Apr. 12, 2019), https://www.doomworld.com/forum/topic/105556-open-sourcing-doom-2016-may-not-happen/.

[16] 17 U.S.C. § 107.

[17] Custom Game Acceptable Use Policy, Blizzard: North America (last updated Jan. 21, 2020), https://www.blizzard.com/en-us/legal/2749df07-2b53-4990-b75e-a7cb3610318b/custom-game-acceptable-use-policy; see also Blizzard End User License Agreement, Blizzard: North America (last revised June 1, 2018), https://www.blizzard.com/en-us/legal/fba4d00f-c7e4-4883-b8b9-1b4500a402ea/blizzard-end-user-license-agreement (“Custom Games” means any custom games, levels, maps, scenarios, or other content created from editing software included in certain games that enable modding).

[18] Matthew Wilson, Take-Two files lawsuit against Red Dead Redemption PC modder, KIT Guru (Dec. 31, 2019), https://www.kitguru.net/gaming/matthew-wilson/take-two-files-lawsuit-against-red-dead-redemption-pc-modder/.

[19] Adi Robertson, Take-Two is suing over a Grand Theft Auto cheating mod – again, Verge (Mar. 21, 2019), https://www.theverge.com/2019/3/21/18274336/grand-theft-auto-online-evolve-mod-menu-cheating-copyright-lawsuit.

[20] Id. See also Steven Messner, Epic Games Sues Creator of “Powerful” Paragon Hack, Rock Paper Shotgun (June 21, 2016), https://www.rockpapershotgun.com/2016/06/21/paragon-hacks-lawsuit/; Alissa McAloon, Epic sues YouTubers for using and selling Fortnite cheats, Gamasutra (Oct. 16, 2018), https://www.gamasutra.com/view/news/328743/Epic_sues_YouTubers_for_using_and_selling_Fortnite_cheats.php. Compare Nintendo’s approach on mods. See note iv.

[21] What is free software?, GNU Operating System / Free Software Foundation (last accessed July 15, 2020), https://www.gnu.org/philosophy/free-sw.html.

[22] /u/EA_Jimtern, Remaster Update and Open Source / Mod Support, Reddit: /r/commandandconquer (May 20, 2020), https://www.reddit.com/r/commandandconquer/comments/gnevp8/remaster_update_and_open_source_mod_support/fr97x9x/; Michael Kan, EA to Open Source PC Game Command & Conquer, Enabling You to Create Crazy Mods, PC Mag (May 20, 2020), https://www.pcmag.com/news/ea-to-open-source-pc-game-command-conquer-enabling-you-to-create-crazy.

[23] Creation Club, Bethesda (last accessed July 13, 2020), https://creationclub.bethesda.net/.

[24] For example, Rockstar Games, a subsidiary of Take-Two, sometimes openly disagrees with Take-Two in its approach to mods based on games from the Grand Theft Auto franchise. In 2017, Rockstar Games negotiated with Take-Two to not take legal action against the creator of a mod that was perceived by Rockstar Games as non-commercial and reasonable fan creativity. The result is ad hoc enforcement against modders. Thomas Biery, Rockstar urges Take-Two to ease off on Grand Theft Auto modders, Polygon (June 23, 2017), https://www.polygon.com/2017/6/23/15864600/rockstar-taketwo-openiv-gta-mod-legal-cease-desist.

[25] Brian Ashcraft, Game Console Modding Illegal in Japan, Punishable by Prison and Fines, Kotaku (Jan. 7, 2019), https://kotaku.com/game-modding-illegal-in-japan-punishable-by-prison-and-1831525943.