Tetris Holding, LLC v. Xio Interactive, Inc.

Last updated

Tetris Holding, LLC v. Xio Interactive, Inc.
Seal for the United States District Court for the District of New Jersey.png
Court United States District Court for the District of New Jersey
Full case nameTetris Holding, LLC and The Tetris Company v. Xio Interactive, Inc.
DecidedMay 30, 2012 (2012-05-30)
Citation(s)863 F.Supp.2d 394 (D.N.J. 2012)
Transcript(s) Opinion
Court membership
Judge sitting Freda L. Wolfson

Tetris Holding, LLC v. Xio Interactive, Inc., 863 F.Supp.2d 394 (D.N.J. 2012), was a 2012 American legal case related to copyright of video games, confirming that a game's look and feel can be protected under copyright law. Tetris Holding is a company that holds the copyright to the original Tetris game from 1985 and licenses those rights to game developers. Xio Interactive is a game developer that released Mino in 2009, a mobile game based on the gameplay of Tetris. Mino was downloaded millions of times, and Tetris Holding filed a DMCA notice and eventually a lawsuit against Xio for copyright infringement.

Contents

The earliest video game case law had protected the designs in Galaxian and Pac-Man . But later cases such as Data East USA, Inc. v. Epyx, Inc. found that it is permissible to make a video game clone with similar ideas and principles as another game, since copyright does not protect an idea, only the specific expression of that idea. A trial occurred in 2012, the first case in a long time to proceed to trial on this issue. The district court ruled for Tetris Holding, with Judge Wolfson applying the Abstraction-Filtration-Comparison test to determine if any infringement occurred. Although standard gameplay ideas are not copyrightable, Mino was still substantially similar to Tetris in terms of its art style, and those elements are in fact protected by copyright. This case has since been applied in other copyright disputes to offer broader protection to the look and feel of video games.

Background

Historical context

In 1985, [1] Alexey Pajitnov created the puzzle game Tetris for the Dorodnitsyn Computing Centre at the Soviet Academy of Sciences. Within a few years Tetris became one of the most successful video games of all time. Henk Rogers was one of the key people who brought Tetris to the world by going to Moscow to negotiate for the rights. Rogers later befriended Pajitnov and helped the two acquire ownership of the copyrights from a former Soviet agency. [2] By the early 2000s, Rogers and Pajitnov created The Tetris Company to control the Tetris intellectual property, and to license their rights to game developers who comply with certain standards. [3]

In 2009, Desiree Golden founded a game studio called Xio Interactive, and released a mobile game called Mino based on the gameplay of Tetris. [4] Xio had tried to license the rights to Tetris from The Tetris Company, who refused. At that point Xio researched intellectual property law to see how to design a game similar to Tetris that would not include any legally-protected elements. [5] The game Mino featured the same approach of using falling tetromino blocks to form complete lines on a playfield and score points. [6] Mino also added new power-ups and game modes to the basic Tetris gameplay. [7] The game's marketing materials described it as a "Tetromino game" with "fast-paced, line-clearing features", and ended with a disclaimer: "Mino and Xio Interactive are not affiliated with Tetris or the Tetris Company". [6]

While there have been many Tetris clones, Mino was eventually downloaded more than six million times. In August 2009, Tetris Holdings sent DMCA notices to Xio via Apple requesting that Apple take Mino down from the App Store. As part of the DMCA process, Xio filed a counter-notice and Apple re-instated the game to their store. Since Apple could not permanently remove the software without a legal order to do so, The Tetris Company filed a lawsuit against Xio Interactive in December 2009 in the United States District Court for the District of New Jersey. [6]

The earliest video game case law was an extension of other copyright cases in media and technology, offering copyright protection to original characters and specific sequences of code, but not to gameplay systems that are essential to create a game. [8] Copyright jurisprudence developed a legal doctrine called the idea–expression distinction, which says that copyright does not protect a general idea, only one expression of an idea. Based on this, copyright does not protect scènes à faire , where stock scenes and generic details are common among creative works. There is also the merger doctrine where some ideas may only have a limited number of ways of being expressed, and it would be legally unfair to protect expression if it effectively gives someone a monopoly on an idea. [9] For this reason, the Copyright Office advises that "copyright does not protect the idea for a game, its name or title, or the method or methods for playing it. Nor does copyright protect any idea, system, method, device, or trademark material involved in developing, merchandising, or playing a game. Once a game has been made public, nothing in copyright law prevents others from developing another game based on similar principles." [10]

These principles had been interpreted to protect the shapes of insect-like aliens in Galaxian , as well as protecting Pac-Man from a copy called K.C. Munchkin! in the 1982 case Atari v. Philips. However, copyright has also been interpreted to allow video game clones that closely matched gameplay concepts as long as their expression was original. [6] This has allowed the creation of games that share many similarities, including World Karate Championship and Karate Champ in the late 1980s (decided in Data East v. Epyx), or Fighter's History and Street Fighter II in the early 1990s (decided in Capcom v. Data East). This has been interpreted to mean that a game's expressive elements are copyrightable, with game mechanics and rules being freely copyable as ideas. [11] With the costs of filing a lawsuit being very high compared to the expected outcome, many video game copyright holders became hesitant to sue alleged clones. Most lawsuits about alleged clones were settled between the mid-1990s and the mid-2000s, and Xio became a rare case that proceeded to trial on this issue. [12]

Ruling

Comparison of Tetris (left) and Mino in Judge Wolfson's analysis, illustrating that the two games put side by side were nearly indistinguishable Mino-tetris-comparison.jpg
Comparison of Tetris (left) and Mino in Judge Wolfson's analysis, illustrating that the two games put side by side were nearly indistinguishable

The case was assigned to Judge Freda L. Wolfson. In defending the copyright claim, Xio founder Desiree Golden admitted to having copied Mino directly from the official Tetris app that was developed under license by Electronic Arts. Golden also admitted that they had sought a license to Tetris from Tetris Holdings, who turned them down. Subsequently, Golden continued to develop Mino based on their understanding of video game case law, and believed that they could avoid infringing on Tetris's expression by creating new audio and video assets. [13]

Judge Wolfson ruled early that, as previously established, the gameplay of Tetris was not copyrightable. The New Jersey district court was within the Third Circuit, which had prior case law from Whelan v. Jaslow (797 F.2d 1222 (1987)) that used a purpose-based test to abstract software to determine if copyright was infringed. Wolfson also explored case law from other circuits, using the Abstraction-Filtration-Comparison test (AFC) for substantial similarity that had been first defined in Nichols v. Universal Pictures Corp. (45 F.2d 119 (1930)) and then applied to computer software in Computer Associates International, Inc. v. Altai, Inc. (982 F.2d 693 (1992)). Two video game cases, Atari v. Philips (related to Pac-Man and an alleged clone K.C. Munchkin!) and Midway Manufacturing Co. v. Bandai-America, Inc. (related to handheld clones of Midway's Galaxian ) were found to have been ruled in the same manner as the AFC test, and Wolfson decided to apply them to Mino. Wolfson explained that the court should compare the games "as they would appear to a layman [by] concentrating upon the gross features rather than an examination of minutiae", essentially comparing the games' respective look and feel; Wolfson further wrote "[i]f one has to squint to find distinctions only at a granular level, then the works are likely to be substantially similar". [9]

Wolfson discussed which aspects of Tetris were copyrightable as expressive elements, and which aspects are part of the general idea that cannot be protected by copyright. According to Wolfson, copyright cannot protect the idea of vertically falling blocks, or a player rotating those blocks to form lines and earn points, or a player losing the game if those blocks accumulate at the top of the screen. However, Wolfson determined that several aspects of Tetris qualify as unique expression that is protected by copyright. This includes the twenty-by-ten square game board, the display of randomized junk blocks at the start of the game, the display of a block's "shadow" where it will land, and the display of the next piece to fall. Wolfson also granted protection to the blocks changing in color when they land, and the game board filling up when the game is over. [7]

With the expressive elements of Tetris under copyright protection, copying one of these elements would not necessarily prove there has been copyright infringement, in isolation. However, Wolfson found that Mino co-opted all of these elements, which had no development purpose "other than to avoid the difficult task of developing its own take on a known idea". [7] In her analysis, Wolfson quickly concluded that Mino failed the AFC test as it looked so similar to Tetris side-by-side. Further, Wolfson rejected the merger doctrine claim that Golden had proposed, since the details of the art style used in the Tetris blocks had "are not part of the ideas, rules, or functions of the game nor are they essential or inseparable from the ideas, rules, or functions of the game." Wolfson further dismissed Golden's scènes à faire arguments, ruling that Tetris was a unique game and thus had no established stock or common imagery that would be ineligible for protection. [9] In weighing these arguments, Wolfson noted that Mino copied Tetris much more closely than a game like Dr. Mario , a game that utilized the rules of Tetris to express a similar idea in a unique and non-infringing way. [14]

Wolfson also examined at Mino's marketing materials to determine if they infringed the trade dress of Tetris. Where Mino's marketing used the same color and style of the pieces from Tetris, these details were distinct expression and not merely functional ideas in the public domain. Wolfson determined that this created a likelihood that consumers would confuse Mino with Tetris, and held that Mino's trade dress was infringing. [9] Wolfson subsequently granted summary judgment in Tetris Holding's favor, [15] and entered an injunction that permanently prohibited Xio from distributing or marketing their game. [16]

Impact

As Golden did not appeal the case to the Third Circuit, the decision is only binding precedent on the District of New Jersey. However other courts have cited the ruling as relevant case law in evaluating other video game cloning cases and have relied upon it to establish a new approach to evaluating copyrights surrounding the look and feel of video games. [6] [11] Legal scholars have included this decision in a wave of cases that have pushed the boundaries of video game copyright protection, along with Electronic Arts Inc. v. Zynga Inc. from 2012. [17] Also in 2012, Spry Fox, LLC v. Lolapps, Inc. was heard in the United States District Court for the Western District of Washington, brought by Spry Fox against developer Lolapps over their game Yeti Town which Spry Fox claimed was a copyright-infringing clone of Triple Town . At the initial hearings, the judge followed similar logic used in the Xio case to order a preliminary injunction in favor of Spry Fox, as Yeti Town had the same look-and-feel as Triple Town when simply viewed side by side. The case was subsequently settled out of court, with Spry Fox gaining ownership of the Yeti Town property by the end of 2012. [11] Since these cases in 2012, legal scholars have found that courts have been more scrutinizing of look-and-feel in cases involving video game clones. [18]

Despite warnings that the case might lead to an explosion of intellectual property disputes and copyright trolls, there has only been an incremental increase, with the courts applying this legal standard carefully to new cases. [14] Nicholas Lampros also noted that the facts of this case were highly specific, leading to "a narrow, fact-heavy legal standard, the outcome of which is difficult to predict outside of court". He added that this would put more onus on digital distribution platforms to manage potentially infringing products. [6] Tom Phillips has noted that the high cost and uncertainty of fact-specific litigation has led developers to hold each other accountable in the media, as an alternative to legal action. [19]

Analysis

Scholars have argued that this case represents the game medium coming of age, evolving from rudimentary gameplay into sufficiently expressive systems that are worthy of copyright protection. [8] This coincides with the legal system having more experience and understanding of video games, where the judge who decided the case was 18 when Pong was released. [12] The ruling shows the courts using a "high level of understanding of video game mechanics for the first time". [14]

Susan Corbett argues that "the Tetris decision supports the view that United States courts are becoming more accepting of the possibility of offering broader copyright protection for videogames". [20] Tomasz Grzegorczyk notes that this case shows courts are willing to recognize that the "graphic user interface of the game is subject to protection under copyright in the same manner as audiovisual works". [21] Noting that the copyright infringing game copied exact shapes and colors, Steven Conway and Jennifer deWinter argue that the decision would not impact other alleged game clones that are less similar. [22] Josh Davenport and Ross Dannenberg suggest that while a "standard game device" may be too generic to warrant copyright protection, that a specific selection or arrangement of those devices would quality as unique expression, and thus be copyrightable. [8] John Kuehl calls this case a potential killing blow to knock off video games that are near copies of the original. [14]

Related Research Articles

<i>Tetris</i> 1985 video game

Tetris is a puzzle video game created by the Soviet software engineer Alexey Pajitnov in 1985. It has been published by several companies for multiple platforms, most prominently during a dispute over the appropriation of the rights in the late 1980s. After a significant period of publication by Nintendo, the rights reverted to Pajitnov in 1996, who co-founded the Tetris Company with Henk Rogers to manage licensing.

Software copyright is the application of copyright in law to machine-readable software. While many of the legal principles and policy debates concerning software copyright have close parallels in other domains of copyright law, there are a number of distinctive issues that arise with software. This article primarily focuses on topics particular to software.

<span class="mw-page-title-main">Video game clone</span> Video game that resembles another video game

A video game clone is either a video game or a video game console very similar to, or heavily inspired by, a previous popular game or console. Clones are typically made to take financial advantage of the popularity of the cloned game or system, but clones may also result from earnest attempts to create homages or expand on game mechanics from the original game. An additional motivation unique to the medium of games as software with limited compatibility, is the desire to port a simulacrum of a game to platforms that the original is unavailable for or unsatisfactorily implemented on.

<span class="mw-page-title-main">The Tetris Company</span> American video game company

The Tetris Company, Inc. (TTC) is the manager and licensor for the Tetris brand to third parties. It is based in Nevada and is owned by Tetris creator Alexey Pajitnov and Henk Rogers. The company is the exclusive licensee of Tetris Holding LLC, the company that owns Tetris rights worldwide.

<i>Computer Associates International, Inc. v. Altai, Inc.</i> American legal case

Computer Associates International, Inc. v. Altai, Inc., 982 F.2d 693 is a decision from the United States Court of Appeals for the Second Circuit that addressed to what extent non-literal elements of software are protected by copyright law. The court used and recommended a three-step process called the Abstraction-Filtration-Comparison test. The case was an appeal from the United States District Court for the Eastern District of New York in which the district court found that defendant Altai's OSCAR 3.4 computer program had infringed plaintiff Computer Associates' copyrighted computer program entitled CA-SCHEDULER. The district court also found that Altai's OSCAR 3.5 program was not substantially similar to a portion of CA-SCHEDULER 7.0 called SYSTEM ADAPTER, and thus denied relief as to OSCAR 3.5. Finally, the district court concluded that Computer Associates' state law trade secret misappropriation claim against Altai was preempted by the federal Copyright Act. The appeal was heard by Judges Frank Altimari, John Daniel Mahoney, and John M. Walker, Jr. The majority opinion was written by Judge Walker. Judge Altimari concurred in part and dissented in part. The Second Circuit affirmed the district court's ruling as to copyright infringement, but vacated and remanded its holding on trade secret preemption.

<i>Stern Electronics, Inc. v. Kaufman</i> American legal case

Stern Electronics Inc. v. Kaufman, 669 F.2d 852, is a legal case in which the United States Court of Appeals Second Circuit held that Omni Video Games violated the copyright and trademark of Scramble, an arcade game marketed by Stern Electronics. The lawsuit was due to a trend of "knock-off" video games in the early 1980s, leading to one of the earliest findings of copyright infringement for a video game, and the first federal appellate court to recognize a video game as a copyrighted audiovisual work.

<i>Midway Manufacturing Co. v. Artic International, Inc.</i> U.S. Court of Appeals case

Midway Manufacturing Co. v. Artic International, Inc., 704 F.2d 1009, was a legal case where the United States Court of Appeals for the Seventh Circuit found that Artic violated Midway's copyright in their arcade games Pac-Man and Galaxian. The lawsuit was part of a trend of "knock-off" video games in the early 1980s, with courts recognizing that a video game can qualify for protection as a copyrighted audiovisual work.

<i>Lewis Galoob Toys, Inc. v. Nintendo of America, Inc.</i> 1992 American court case on copyright

Lewis Galoob Toys, Inc. v. Nintendo of America, Inc. is a 1992 legal case where the United States Court of Appeals for the Ninth Circuit concluded that there was no copyright infringement made by the Game Genie, a video game accessory that could alter the output of games for the Nintendo Entertainment System. The court determined that Galoob's Game Genie did not violate Nintendo's exclusive right to make derivative works of their games, because the Game Genie did not create a new permanent work. The court also found that the alterations produced by the Game Genie qualified as non-commercial fair use, and none of the alterations were supplanting demand for Nintendo's games.

<i>Sega v. Accolade</i> 1992 American court case

Sega Enterprises Ltd. v. Accolade, Inc., 977 F.2d 1510, is a case in which the United States Court of Appeals for the Ninth Circuit applied American intellectual property law to the reverse engineering of computer software. Stemming from the publishing of several Sega Genesis games by video game publisher Accolade, which had disassembled Genesis software in order to publish games without being licensed by Sega, the case involved several overlapping issues, including the scope of copyright, permissible uses for trademarks, and the scope of the fair use doctrine for computer code.

<i>Data East USA, Inc. v. Epyx, Inc.</i> 1988 legal case

Data East USA, Inc. v. Epyx, Inc. 862 F.2d 204, 9 U.S.P.Q.2d (BNA) 1322 was a court case between two video game manufacturers, where Data East claimed that their copyright in Karate Champ was infringed by World Karate Championship, a game created by Epyx. Data East released Karate Champ in arcades in 1984, and the game became a best-seller and pioneered the fighting game genre. The next year, Epyx published World Karate Championship for home computers, which sold 1.5 million copies. Data East sued Epyx, alleging that the game infringed on their copyright and trademark.

<i>Micro Star v. FormGen Inc.</i> 1998 American court case on copyright

Micro Star v. FormGen Inc. 154 F.3d 1107 is a legal case applying copyright law to video games, stopping the sales of a compilation of user-generated levels that infringed the copyright of Duke Nukem 3D. Micro Star downloaded the Duke Nukem 3D levels and re-packaged them as Nuke It, after seeing their popularity on the internet. Micro Star filed suit in the United States District Court for the Southern District of California, asking for declaratory judgment that they had not infringed any copyright. Game publisher FormGen counter-sued, claiming that Micro Star created a derivative work based on Duke Nukem 3D and infringed their copyright.

<i>Triple Town</i> 2010 video game

Triple Town is a freemium strategy puzzle video game with city-building elements. It is available for social networks and mobile devices and was developed by Seattle-based Spry Fox.

The Ville is a defunct game by Zynga released on June 30, 2012 in which the object was to earn experience points by building a house and talking with neighbors.

<i>Atari Games Corp. v. Nintendo of America Inc.</i> Legal dispute between Atari and Nintendo

Atari Games Corp. v. Nintendo of America Inc., 975 F.2d 832, is a U.S. legal case in which Atari Games engaged in copyright infringement by copying Nintendo's lock-out system, the 10NES. The 10NES was designed to prevent Nintendo's video game console, the Nintendo Entertainment System (NES), from playing unauthorized game cartridges. Atari, after unsuccessful attempts to reverse engineer the lock-out system, obtained an unauthorized copy of the source code from the United States Copyright Office and used it to create its 10NES replica, the Rabbit. Atari then sued Nintendo for unfair competition and copyright misuse, and Nintendo responded that Atari had engaged in unfair competition, copyright infringement, and patent infringement.

<i>Atari Games Corp. v. Oman</i> 1992 court case regarding video game copyright law

Atari Games Corp. v. Oman was a series of court cases where Atari, a video game developer, challenged the United States Copyright Office for refusing copyright registration for their arcade game Breakout. The Register of Copyrights first rejected Atari's registration in 1987, determining that Breakout lacked sufficient creativity to qualify as an audiovisual work. Atari twice appealed the register's decision before their copyright was granted. Decided in 1992, the case affirmed that video games are protected from clone developers who mimic a game's audiovisual aspects.

The protection of intellectual property (IP) of video games through copyright, patents, and trademarks, shares similar issues with the copyrightability of software as a relatively new area of IP law. The video game industry itself is built on the nature of reusing game concepts from prior games to create new gameplay styles but bounded by illegally direct cloning of existing games, and has made defining intellectual property protections difficult since it is not a fixed medium.

<i>Capcom U.S.A. Inc. v. Data East Corp.</i> 1994 legal case

Capcom U.S.A. Inc. v. Data East Corp., 1994 WL 1751482 was a 1994 legal case related to the copyright of video games, where Capcom alleged that Data East's game Fighter's History infringed the copyright of Capcom's game Street Fighter II. It was revealed that the design documents for Fighter's History contained several references to Street Fighter II, leading Capcom to sue Data East for damages, as well as a preliminary injunction to stop the distribution of the infringing game. In spite of the intentional similarities between the two games, the court concluded that Data East did not infringe upon Capcom's copyright, as most of these similarities were not protected under copyright. Judge William H. Orrick Jr. applied a legal principle known as the merger doctrine, where courts will not grant copyright protection where it would effectively give someone a monopoly over an idea.

<i>Spry Fox, LLC v. Lolapps, Inc.</i> 2012 American legal case

Spry Fox, LLC v. Lolapps, Inc., No. 2:12-cv-00147, was a court case between two video game developers, where Spry Fox alleged that the game Yeti Town, developed by 6waves Lolapps, infringed on their copyrighted game Triple Town. While the case was settled out of court, preliminary opinions by Judge Richard A. Jones affirmed that a video game's "look and feel" may be protected by copyright, affirming the federal district court decision in Tetris Holding, LLC v. Xio Interactive, Inc. from earlier the same year.

<i>Atari, Inc. v. North American Philips Consumer Electronics Corp.</i> 1982 legal case

Atari, Inc. v. North American Philips Consumer Electronics Corp., 672 F.2d 607, is one of the first legal cases applying copyright law to video games, barring sales of the game K.C. Munchkin! for its similarities to Pac-Man. Atari had licensed the commercially successful arcade game Pac-Man from Namco and Midway, to produce a version for their Atari 2600 console. Around the same time, Philips created Munchkin as a similar maze-chase game, leading Atari to sue them for copyright infringement.

<i>Atari v. Amusement World</i> 1981 legal case

Atari Inc. v. Amusement World Inc., 547 F.Supp. 222 is a legal case in which the United States District Court for the District of Maryland held that Amusement World's arcade game Meteors did not violate Atari's copyright in their game Asteroids.

References

  1. "Tetris | video game | Britannica". www.britannica.com. Retrieved 2023-04-19.
  2. October 2016, Mindy Weisberger 13 (13 October 2016). "The Bizarre History of 'Tetris'". livescience.com. Retrieved 2021-02-14.
  3. Metts, Jonathan (2006-04-06). "Tetris from the Top: An Interview with Henk Rogers". Nintendo World Report. Retrieved 2014-04-17.
  4. Lampros, Nicholas (2013). "Leveling Pains: Clone Gaming and the Changing Dynamics of an Industry". Berkeley Technology Law Journal. 28: 743.
  5. "Judge Declares iOS Tetris Clone 'Infringing'". Wired. ISSN   1059-1028 . Retrieved 2021-02-14.
  6. 1 2 3 4 5 6 Lampros, Nicholas M. (2013). "Leveling Pains: Clone Gaming And The Changing Dynamics Of An Industry" (PDF). Berkeley Technology Law Journal . 28: 743–774. Archived (PDF) from the original on July 28, 2020. Retrieved January 19, 2021.
  7. 1 2 3 Orland, Kyle (20 June 2012). "Defining Tetris: How courts judge gaming clones". Ars Technica .
  8. 1 2 3 Dannenberg, Ross; Davenport, Josh (2018-12-01). "Top 10 video game cases (US): how video game litigation in the US has evolved since the advent of Pong". Interactive Entertainment Law Review. 1 (2): 89–102. doi: 10.4337/ielr.2018.02.02 . ISSN   2515-3870.
  9. 1 2 3 4 Casillas, Brian (2014). "Attack Of The Clones: Copyright Protection For Video Game Developers". Loyola of Los Angeles Entertainment Law Review. 33: 137–170. Archived from the original on April 6, 2019. Retrieved January 19, 2021.
  10. "U.S. Copyright Office – Games". United States Copyright Office. Archived from the original on 2014-02-09. Retrieved 2012-08-07.
  11. 1 2 3 McArthur, Stephen (2013-02-27). "Clone Wars: The Six Most Important Cases Every Game Developer Should Know". Gamasutra. Archived from the original on 2013-03-02. Retrieved 2013-02-27.
  12. 1 2 Quagliariello, John (2019). "Applying Copyright Law to Videogames: Litigation Strategies for Lawyers" (PDF). Harvard Journal of Sports and Entertainment Law. 10: 263.
  13. "Judge Declares iOS Tetris Clone 'Infringing'". Wired . June 21, 2012. Archived from the original on August 9, 2020. Retrieved January 19, 2021.
  14. 1 2 3 4 Kuehl, John (2016). "Video Games and Intellectual Property: Similarities, Differences, and a New Approach to Protection". Cybaris. 7 (2): 313–349.
  15. McArthur, Stephen (27 February 2013). "Clone Wars: The Five Most Important Cases Every Game Developer Should Know". Gamasutra .
  16. "The Tetris Co. wins ruling in video game copyright case against Xio Interactive". Pacific Business News. February 4, 2013.
  17. Castree, Sam III (September 8, 2013). "A Problem Old as Pong: Video Game Cloning and the Proper Bounds of Video Game Copyrights". SSRN   2322574.
  18. Dean, Drew S. (215). "Hitting reset: Devising a new video game copyright regime". University of Pennsylvania Law Review . 164: 1239–1280. Archived from the original on August 7, 2019. Retrieved January 19, 2021.
  19. Phillips, Tom (2015-04-03). ""Don't clone my indie game, bro": Informal cultures of videogame regulation in the independent sector". Cultural Trends. 24 (2): 143–153. doi:10.1080/09548963.2015.1031480. ISSN   0954-8963. S2CID   145650507.
  20. Corbett, Susan (2016). "Videogames and their clones – How copyright law might address the problem". Computer Law & Security Review. 32 (4): 615–622. doi:10.1016/j.clsr.2016.05.001.
  21. Grzegorczyk, Tomasz (2017). "Qualification of computer games in copyright law". Zeszyty Naukowe Wyższej Szkoły Finansów i Prawa w Bielsku-Białej. 21 (1): 131–145. doi:10.19192/wsfip.sj1.2017.9.
  22. Conway, Steven; deWinter, Jennifer (2015-10-14). Video Game Policy: Production, Distribution, and Consumption. Routledge. ISBN   978-1-317-60722-9.