Open 3D Engine and how to use open-source software in video games

You might have already heard that there is a new 3D video games engine dedicated to the development of high-budget and high-quality (AAA) games – called Open 3D engine (O3DE). It is not exactly ‘brand-new’ – it is based on a modified version of Amazon Games’ Lumberyard engine (which, by the way, is a modified CryEngine). What is interesting about this engine, however, is that it is not only free to use, but also open-source.

It is yet another example of open-source software available to video games developers. But what does ‘open-source’ mean and what do you have to keep in mind when creating games with open-source software? In this short article, we would answer these questions, based on the O3DE example.

Open-source licence – what are the implications?

In theory, open-source software is a type of software that is distributed (by the licensor) under a licence that allows the user (licensee) to use (access), change and distribute the software and its source code. This facilitates the developers’ (programmers’) collaboration in the process of software development and saves time for programmers. As great as it sounds, it is not so straightforward in practice. Not every open-source licence provides the same level of freedom.

There are numerous licences which are considered open-source. For example, the list of licenses approved by the Open Source Initiative (i.e. meeting OSI’s Open Source Definition) includes over 100 licences (the list is available here). The most popular ones that one might come across online (e.g. on GitHub) are probably Apache, BSD, GNU and MIT licences.

All of the listed licences are considered open-source but the terms that they license software on vary, sometimes significantly. Open-source licences often contain important limitations which might make the way you want to use the software illegal. Therefore, the first lesson regarding the open-source licences is the following: always check what the licence is that the particular piece of software (source code or object code) is distributed on.

With that in mind – what licences is Open 3D Engine distributed on?

General Open 3D Engine licences – permissive open-source

When we look to the O3DE’s Github repository, in the ‘LICENSE.txt’ file we can see that the default and general licence for O3DE is the Apache 2.0 license, but the developers can also choose to use O3DE under MIT licence. All future contributions to the repository have to be made under both of these two licences. Fortunately, both Apache 2.0 and MIT licences are actually very permissible. Let us dive into the terms of both these licences.

Apache 2.0

Apache 2.0 licence gives the licensee a following set of rights:

“perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form”

(capitalised terms are defined in the licence text).

It also gives the licensee a patent licence (if there is any patent) which is very similar in scope.

Reproduction of the software and its source code (modified or not) has to meet the following requirements:

  1. every recipient must receive a copy of the licence (e.g. in a “license.txt” file attached to the program);
  2. every file you modified must carry a notice stating that you have done so;
  3. you must keep all the previous copyright or patent notices included in the files;
  4. you must further distribute the “NOTICE” text file, containing all the relevant attribution notices.

In relation to contributions, all contributions to the Apache-licensed software are also deemed Apache-licensed, unless the contributor states otherwise. In the case of O3DE, the general licence requires developers to share contributions on both Apache 2.0 AND MIT licenses, so this rule has been overridden by the general O3DE licence.

The licence also includes provisions on the use of licensor’s trademarks (in short: do not use any if you are not explicitly permitted to do it), limitations of liability and warranties, as well as the instructions on how to apply the Apache licence to the work created by licensee.

Nothing in the licence restricts the use of the source code in commercial projects. In short, what Apache licence requires is that you include in your software the information that you use the Apache-licensed software, the information that you modified it (if you did), all attribution notices and the copy of the licence text. You do not have to share the modifications or any other part of the source code publicly.


At first glance, the MIT licence is much simpler and significantly shorter than the Apache 2.0 licence. It grants free of charge the rights “to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so”. The set of rights is similar in spirit to the one in the Apache licence, but there are some differences in the wording.

Compared to Apache 2.0, the permission to use the software in the ways described above is made under one condition only: “The above copyright notice [that is: the notice stating who is the copyright holder of the software – in O3DE’s case “Copyright Contributors to the Open 3D Engine”] and this permission notice shall be included in all copies or substantial portions of the Software”.

In short: you can use and modify the source code distributed under MIT license however you like, even in commercial products, as long as your software includes the full text of the copyright notice and permission notice.

Copyleft and engine plugins – what to pay attention to

Unfortunately, not all open-source software is distributed on such permissive licences as MIT or Apache 2.0. Developers have to be aware in particular of the so-called “copyleft” licences, of which the most popular is the GNU license family. There are too many issues regarding copyleft licences to discuss in this short article, however as O3DE licence text explicitly discusses this topic and because of the risks associated with it, short description is required.

In general, copyleft licences are the licences that include the requirement that the derivative works created based on the work distributed on such licences are distributed on the same terms (same licence). In short, this means that if you use the source code licensed on a copyleft licence in the computer program, due to the rule which is sometimes called the ‘copyleft virus’, you might be required to distribute your program (the rest of the code) on the same copyleft licence, for example for free. This ‘infection’ is a huge risk for proprietary (commercial) software and it is also present to some extent in the case of Open 3D Engine.

There is a very important disclaimer in the O3DE licence text, which can be seen in full below:

Open 3D Engine requires the use of (and in some cases makes available to you) software and assets that have been developed by third parties and are subject to separate license terms (such as code licensed under other open source licenses). It is your responsibility to comply with the applicable licenses. Information on third party materials, and the applicable license terms, are referenced in or included with the materials, such as in separate LICENSE.txt files accompanying the materials.

Please note that certain materials are subject to “copyleft” licenses, which require distribution of source code, including:

– Qt Toolkit, which is subject to the GNU Lesser General Public License version 3 (with certain exceptions). A copy of the source code for Qt Toolkit may be found at

– The AWS Python SDK uses Chardet, which is subject to the GNU Lesser General Public License version 2.1. A copy of the source code may be found at

It means that although the O3DE is open-source and distributed on quite permissive licences, it may require (and does require) the use of software and assets which may be subject to separate licence terms, which often are distributed on much stricter licenses. Before you decide to use O3DE, check the repository for other licences.

General O3DE licence text provides two examples of materials (Qt Toolkit and Chardet) that are distributed on GNU LGPL licence (v. 2.1 and 3.0). Without going into too much detail, in contrast to GNU GPL, the LGPL licence allows the use of LGPL-licenced library to be used in the proprietary products, as long as your work is not a derivative work of the LGPL-licensed work. It is a matter of legal discussion whether in a particular case there would be a derivative work created, but generally it is understood that dynamic linking to the LGPL-licensed library does not create a derivative work but rather is a “work that uses the Library” (using the wording of the licence). This would probably be the case when the engine uses some outside tools and does not incorporate their source-code into the proprietary software, but important disclaimer has to be made: every case is different and the interpretation in a particular case might be different.

As you can see, using copyleft-licensed materials in proprietary works is a legal minefield. The general lesson is that you should always check what other licences are in play and whether they allow you to use software in the way you have imagined and how they might impact other parts of software you develop. Generally, when possible, it is recommended to avoid using copyleft licences in proprietary software. If you want to use copyleft software in your software, it is recommended you consult the IP lawyer and – at the very least – analyse the licence terms very carefully before you decide to use the software.


There is a myriad of different licences which might be applicable in case of open-source software and if the developer wants to use software distributed on proprietary licences in addition to self-developed and open-source software as well, it adds another layer of difficulty, because every proprietary software has different rules of its use. Managing the use of software in a development project is therefore a complex matter which requires thorough examination and a careful approach.

A recommended practice is to create a list of all third-party software used and create guidelines within the organisation regarding which software licences are accepted to use and which are not. The crucial moment in the management of software licences is the moment that the software (the video game, but also any later update) is released to the public. At this moment, any licensor can potentially get to know that the developers have inappropriately used his code. We recommend to check the code in this regard at least once before every release. Many open-source licences require the attribution of licensor’s rights at the minimum, so such an internal audit would be required to carry out this obligation.

If you happen to come by with any issues when using O3DE or any other open-source software in your projects, we recommend you contact a lawyer, for example the LegalPlay team at KL&M LAW.

Ubisoft sues Apple and Google – another episode of clone wars

Recent days have brought us another interesting news in the video games industry. Media report that Ubisoft sued Google and Apple. The case concerns a mobile game called Area F2, made by Chinese developer, which belongs to the Alibaba company. According to the lawsuit, the mobile game is a “carbon copy” of popular Tom Clancy’s Rainbow Six: Siege game, released on consoles and PC. Ubisoft’s statements are hard to deny – the similarity is striking. In this article I will present, which legal arguments could be used by Ubisoft against Chinese developer and why we see Apple and Google on the defendants side and not and Alibaba.

Games cloning is a phenomenon which has existed almost as long as the video game industry itself. There are numerous cases of games being blatant copies or imitations of popular titles. First disputes regarding such games appeared as early as in the ‘70s and are related with the legendary game Pong. Nowadays, the problem of clones is particularly noticeable on the mobile games market. Lower costs of production, as well as easier and cheaper process of releasing games on Google Play or AppStore have caused these marketplaces to be flooded with games openly “inspired” by other popular titles.


Games cloning is an issue particularly complex to address from copyright’s point of view. The border between legal inspiration and illegal infringement is very fluid. Copyright does not give protection to ideas, methods or rules. Only specific, creative expression of an idea is protected. Therefore, copying the mechanics of one game in another does not infringe copyright as long as no protected elements of the game are copied, such as art, music, assets or source code.

Not every element of the game normally protected by copyright will be protected in a particular case. It may turn out that apart from the mechanics of the original game, the creators of the clone only copied elements typical for the genre, such as first-person view in the shooter or spellcasting in the fantasy game. These elements are not usually protected by copyright. In the US, such elements are known as scènes à faire, elements almost mandatory in a particular genre. In Poland, we would probably recognise such elements as not creative because of their prevalence in numerous works.

Other intellectual property rights

Other intellectual property rights may be more appropriate to protect a video game from cloning. Clone creators often use similar or even identical names and icons for their productions to lure the consumer to their game. One way to protect yourself against such practice may be to register the name of the game, its logo or icon, and even the names and images of game characters as trademarks. This may effectively discourage cloning or provide for an easier way to prove an infringement in a case when a clone is created. If the game mechanics are truly innovative, it is also worth to consider registering them as a patent (this is what Techland has done with the movement mechanics in Dying Light).

Unfair competition

In a situation when clone developers have not infringed upon copyright or any other intellectual property rights, there is one more legal weapon in clone wars – unfair competition law. Release of the clone may be considered as an act of unfair competition. Clones often try to mislead the consumer that the game comes from a developer which is particularly renowned on the market, either by misleading label on the platform or by passing off. Such behaviour is prohibited. The developers of the original game are entitled to claims for stopping the infringement, remedy, damages or a declaration of an infringement from the clone developers.

The liability of Apple and Google

Based on the rules of the liability of clones’ developers and publishers for infringing rights of game developers and publishers why then in the case of Area F2 Ubisoft sued Apple and Google, not and Alibaba?

Apple and Google are Internet service providers, AppStore and Google Play respectively, which enable users to buy or download for free games (in this case, clones) directly from their platforms. According to reports, Ubisoft has sent notices to both companies, demanding the takedown of the game from their services. Tech giants did not react to the French publisher’s demands. According to the US Digital Millennium Copyright Act (analogous act in Europe is the so-called e-commerce directive), in case of no reaction to the notice regarding takedown of copyright-infringing materials (e-commerce directive is not limited only to copyright infringements), Internet service providers are liable for the infringement like the direct infringer French publisher probably hopes for the lawsuit to force the giants to react to the emergence of such clones in the future.

Clone wars – a battlefield report

As I mentioned in the introduction, disputes regarding clones have been present in the US almost from the beginning of the video games history. At the beginning of the’80s there was a dispute regarding the cult arcade game– Asteroids. The company called Amusement World created, in the opinion of its author, Stephen Holniker, a superior copy of the game, called Meteors. Atari, the publisher of Asteroids, saw Meteors at the trade fair and decided to file a lawsuit against Amusement World for copyright infringement. To a surprise of many, Atari suffered a defeat. Thanks to this case we got a precedent ruling that the idea for a video game is not protected and as long as there is no copying of particular protectable elements of the game, there is no infringement. The decision in this case opened the doors for the creation and publishing of copies of famous video games. For decades, courts have not really departed from the argumentation presented in this judgement.

Asteroids (left) and Meteors

Chances for a change have appeared at the turn of the first and second decade of the 21st century. The case that expressed a different approach to games cloning concerned a different legend – Tetris. In 2009 a company called Xio published a Tetris clone – a game called Mino. Xio’s production was indistinguishable at first sight from Tetris, even though all its elements which were protected with copyright– art and sounds – have been substituted. Deviating from the accepted practice, the court decided to make an overall assessment of the “impression” that a clone makes on its recipients. Following the court’s line of reasoning, it is therefore not enough to make minor changes to the original to avoid liability for video game’s copyright infringement.

Tetris vs Mino (source)

Similar conclusions can be drawn by looking at Spry Fox v. 6Waves case. The dispute concerned a game called Yeti Town, which copied the game mechanics of a title called Triple Town, however significantly changed the art and setting of the game. Although the case has ultimately ended with a settlement, the court’s decision which allowed for the trial suggested a similar approach as in the case of Mino game. The court has drew his attention not only to the protected elements of the game, but also to the game mechanics and the impression of the recipients, supported by bloggers’ opinion who have pointed out the striking similarity between both titles. The decision of the court has been also influenced by the name of the disputed game and the fact, that the publisher of Yeti Town was initially supposed to publish Triple Town at social media platforms, but the negotiations between the parties have failed.

Triple Town vs Yeti Town (source)


Games cloning is a morally wrong, but incredibly lucrative business and unfortunately it does not seem like it could end soon. Clone developers save time on the process of designing games, which allows them to make quick money. Clones may sometimes even be used as a tool for defrauding personal information or offences against minors, which has been shown by recent example of Club Penguin clones. Apple and Google, as the “gatekeepers’ of their ecosystems do not want to create an image that it is hard for developers to access their platforms, which could discourage devs to create games for their platforms.

It is hard to tell what would be the final result achieved by Ubisoft in a case which has become an inspiration for publishing this article. Proving a copyright infringement, which is required for tech giants’ liability might be very hard. For sure, the publisher counts on a similar outcome as in the Triple Town case. As in the case of this simple game, the cloning is evident, and the opinions of Internet users are unequivocal. No matter the end result, Ubisoft has managed to score a first win – decided to delist the Area F2 from App Store i Google Play to „carry out improvements in order to deliver a better experience to players”. It is very likely that this result will satisfy the publisher and the suit will be withdrawn, and the controversial game will come back online thoroughly changed.

Not everyone is “lucky” to be as big and as respectable as Ubisoft. It is therefore worthwhile to discourage others from cloning our game in advance, for example by securing rights to some of its elements. Regardless of the legal measures, it is also important to be aware of the danger and prepare for possible cloning of our title, for example by planning the game’s release cycle in such a way that the original game will appear on key markets first.

Can LeBron James’ tattoos be replicated in sports video games?

From the video games industry perspective, the coronavirus lockdown does not seem to impact the operation of US courts. In last weeks, we got a few important decisions. One of them, described here on LegalPlay in the previous post, concerned the use of Humvees in Call of Duty games (and, more broadly, the use of trademarks in video games). Today, we would like to focus on the other one. It concerns the second best selling video game title in the US – NBA 2K series – and another American icon – LeBron James.

Tattoos could be considered a source of potential legal issues. As a work, they are usually protected by copyright. In general, the copyrights to the tattoo belong to the tattoo artist. As a result, the artist has a right (for example) to decide how the tattoo is disseminated or whether the person on which the tattoo is inked can remove or modify it. As the tattoos are placed on human body, it could lead to a conflict between copyright, publicity rights and a right to make decisions regarding one’s own body. The problem is not new – in the United States, there were cases involving the famous Mike Tyson’s face tattoo presented in The Hangover Part II or Carlos Condit’s tattoo presented in UFC Undisputed 3 video game. However, all past cases were settled – no final decision was made by the court. This time, the court had a chance to speak, and its decision would certainly make the gaming industry happy.

NBA 2K is the best-selling video game series which aspires to simulate the feeling of a professional NBA basketball game. 2K Games (and Take-Two, its owner), the publisher of the video games series, was sued by the company called Solid Oak Sketches. Solid Oak Sketches has acquired from their authors exclusive licenses to copyrights of five tattoos of three different basketball players – LeBron James, Eric Bledsoe and Kenyon Martin. Solid Oak claimed that 2K has infringed upon its copyrights when it included these five tattoos in their games without a license from Solid Oak.

In its defense, 2K has claimed that it was actually legal for 2K to include players’ tattoos in their games and it had three different legal bases to do so. Firstly, it argued that the use of the tattoos was de minimis and therefore not infringing. Secondly, it claimed that it had acquired implied licenses from the players to present their tattoos in the games. Finally, it held that 2K’s use of the tattoos was fair use under US copyright law.

Judge Swain has agreed with the publisher on all three arguments and included a great explanation of every one of them. To understand the decision, it is best to analyse these findings separately.

De Minimis Use

For a US court to find a copyright infringement, two matters must be demonstrated: that the defendant actually copied the plaintiff’s work and that the copying is illegal because there is a substantial similarity between the defendant’s work and the protectible elements of the plaintiff’s work. The first part is indisputable here – the tattoos were in fact copied in NBA 2K video games. However, the second part is more problematic for Solid Oak. To be substantially similar, the copying must be more than de minimis.

For the copying to be de minimis, the copying of the copyrighted material must be trivial. In the analysis of this issue, the court took into account the following circumstances: the amount of the copyrighted work that is copied, the observability of the copyrighted work and factors such as “focus, lightning, camera angles, and prominence”. To reach a decision in this, Judge Swain also employed an ordinary observer test.

Application of all these rules led the court to hold that the use of tattoos was de minimis. No reasonable lay person would say that the tattoos in games were substantially similar to those licensed to Solid Oak. The tattoos appear only on three players out of over 400 available in the games. The tattoos in games are very small – they are 4.4% to 10.96% of their real-life size. When they appear, their display is small and indistinct, because they appear in the environment of a dynamic basketball game. All these factors considered, the use of tattoos was de minimis.

Implied license

2K held that it had an implied license to feature the tattoos as part of the players’ likenesses. The tattooists who made the tattoos admitted that they knew when they were inking them on players’ bodies that players were likely to appear in public or in media presenting their works. Therefore, the artists gave non-exclusive licenses to the players to use the tattoos as part of their likenesses. Players have then granted NBA the right to license their likeness to third parties. NBA granted such license to the creators of NBA 2K. Additionally, the players also gave direct permission to 2K to use their likenesses in the games.

Because all these actions were taken before Solid Oak was granted the copyrights to tattoos, the court concluded that 2K Games were granted an implied license to use tattoos in the games.

Fair use

Determination whether the use of the copyrighted work is fair use and therefore not infringement, requires consideration of four factors: the purpose and character of the use, the nature of the copyrighted work, the amount and the substantiality of the portion used in relation to the copyrighted work as a whole and the effect of the use upon the potential market for or value of the copyrighted work.

Judge Swain held that the use of tattoos in the game was transformative – they were used for a purpose of recognizability of players in the game, which is a different purpose than that for which they were originally created. Once again, it has been pointed out that in-game tattoos are much smaller and harder to recognise as they appear only as glimpses on the screen. 2K has even provided the data that five disputed tattoos “comprise only 0.000286% to 0.000431% of the total game data”. Even if the use of the tattoos in the game was commercial, consumers do not buy the game because it includes players’ tattoos.

As to the nature of the copyrighted work, the court held that tattoo designs are in fact more factual that expressive, because each of them is based on some other factual work or includes motifs frequently used in tattoos, like flames. Such consideration makes it more likely for the fair use to be found. The court also held that in this case, the copying of entire works was necessary for the purpose of fair use – to make the game more realistic, so this factor does not weigh against the developers. Lastly, the court held that the transformative use of the tattoos in video games does not harm the market for “real” tattoos. There is also no market for licensing tattoos for the use in video games because no developers enters into this kind of agreements. All four factors weigh in 2K Games favor, therefore the court concluded that there was fair use in the disputed case.

2K Games scored a big win in this legal match. The judge has decisively held that the developers have legal right to show copyrighted tattoos if they acquired the license to feature players’ likenesses. This decision would certainly discourage other entities like Solid Oak Sketches, which planned to make money out of licensing tattoos for use in games or other media. The freedom of artistic expression has once again been protected. It is also a good sign that the video games industry is determined to fight for their rights in courts, therefore enriching the case law and helping other developers in similar situations. Unfortunately, district court decisions do not create binding precedents, so it is still safer for a tattooed person to get a written release from the tattooist than worry later.

In Poland, the copyright protection awarded to tattoos is similar. The dispute regarding Mike Tyson’s face tattoo, mentioned in the introduction, could have appeared in Poland as well, because famous Polish energy drink manufacturer has put the boxer’s likeness on drinks’ cans. The author of the tattoos could potentially impact the use of the tattoo. The person on which the tattoo is inked should keep in mind that in Poland, the tattoo artist also has moral copyrights, which give him even more ways to influence the use of a tattoo. On the other hand, one could argue (as it was argued in the case) that the tattoo artist is usually aware that the tattoo may be shown on person’s body in different situations and therefore gives the person an implied license to use it as part of its’ likeness.

This court decision is not final as it could still be appealed by Solid Oak Sketches, however according to Solid Oak’s attorney, it seems unlikely.

The decision can be read in full here.