I did some searching around, specifically on this website actually, and I am a bit confused on this:

If you were to reverse engineer a private server and make no money off of it (except maybe donations to keep the server running), could you get a law suit filed against you?

The reason why I'm asking is because I see a lot of different answers that range from maybe to you're violating the copyright laws. There's a private server I play on called Wonderland Online Reborn. They remade the game and it's been out for a while and they've had nothing pressed against them to my knowledge. The game that they, "rebirthed," shut down a few years back, hence the name wonderland online reborn. The company that shut it down is quite greedy and had a lot of pay to win mechanics, wonderland online reborn removed all the pay to win mechanics and now it's simply something you play for fun and the servers are kept running by donations.

Another similarity to this is Toontown rewritten, why aren't they taken down? Specifically because they're not making money off of it? Becuase they've changed enough things for it to no longer be considered copyright infringement?

I'm just confused, I'd like to know the actual answer/ answers. A game I am quite passionate about kind of sucks right now and will probably die soon. I would want to know if I'm allowed to remake that game (even if just for myself) if the server code ever got leaked or if I could reverse engineer the server code.

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    Short answer is "yes", you would still be liable for tortious interference in the contractual relationship between the users of the game client and the operators of the original game servers. But this is already covered by answers to other similar questions on this site.
    – grovkin
    Feb 7, 2021 at 6:21
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    Does this answer your question? How can one open a profitable MMORPG private server (server emulator) legally? You can find many similar questions by doing a search for "game server" on this site.
    – grovkin
    Feb 7, 2021 at 6:23
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    This seems significantly different in that it is asking abo0ut servers for games no loner being actively run by the original developers, which has some effects on the legal position. I do not think it should be closed as a duplicate. Feb 7, 2021 at 18:13
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    @grovkin You say " Someone still owns the IP". True. But what is that IP? Primarily a copyright. It is not a contract. IP is not an exclusive right to make money out of an idea. Game rules and mechanics are not protected by copyright. If there are no current contracts to interfere with, there can be no claim for tortious interference. Even if I am mistaken about that, that is an issue simply not addressed in the linked answers, which makes this not a duplicate. Feb 9, 2021 at 14:49

2 Answers 2


There are at least three different grounds on which someone running a private game server without permission might be successfully sued by the original developers or operators of the game. These are Copyright infringement, Trademark infringement, and Interference with contracts.

Copyright Infringement

It is unlawful to make a copy of a protected work without permission. It is also unlawful to make a derivative work from a protected work without permission.

If a server is reverse-engineered starting only with the observable behavior, it is probably not a copy in the sense used in copyright law.

US copyright law (17 USC 101) says:

A “derivative work” is a work based upon one or more preexisting works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which a work may be recast, transformed, or adapted. A work consisting of editorial revisions, annotations, elaborations, or other modifications, which, as a whole, represent an original work of authorship, is a “derivative work”.

The law in other countries is similar.

However, reverse-engineering has in a number of US cases been held to be a fair use. This is a strictly US legal concept which does not apply elsewhere. Sega Enterprises v. Accolade and Sony Computer Entertainment v. Connectix held that in particular circumstances reverse engineering of video game systems to allow interoperability was a fair use. However in Compaq Computer Corp. v. Procom Technology, Inc. and Blizzard v. BnetD reverse engineering efforts were held to be improper. In the Blizzard case this was based on violations of the ELUA and ToS by people who had agreed to them, and then proceeded to do reverse engineering contrary to specific provisions of those agreements.

Whether something is is a complex, fact-driven issue. Anyone planning on undertaking such an effort based on a fair-use claim would be wise to secure competent legal advice in advance.

Some non-US countries have a legal concept of fair dealing which is somewhat similar to, but more limited than, the US concept of fair use.

Trademark Infringement

The name of a published game is usually a protected trademark. Logos, images, slogans, and tag lines may also be protected as trademarks. Using a trademark to advertise a competing product – even a free one – is trademark infringement.

However, if the original product is no longer on the market, its trademark protection may have lapsed. Trademarks are only protected when 'used in commerce". If the mark is no longer used, and there is no indication of future intent to use the mark, it may no longer be protected.

If a trademark is used in a comparative sense such as a statement that "Game X is more fun than Game A" this is generally not trademark infringement, as long as no reasonable person would be confused into thinking that the product or service was made by, authorized by, or endorsed by the makers of the protected product. This sort of use is generally limited to the name, and does not permit the use of a logo or other image, nor of slogans or the like.

Similarly, a product may be described as being compatible with a product from a different source, without this being trademark infringement. (E.g., "Battery A can be used with Brand X tools"; "GreatBlade fits all SmoothShave razors.")

Both of these are examples of Nominative use.

Relying on a determination that a mark has lapsed can be tricky, and it would be wise to consult a trademark lawyer before doing so. Nominative use is a bit clearer, but consulting an expert is still often wise. Both of these are fact-based situations and different cases may come out differently.

Interference with Contracts

If an existing game operator has contracts with game users, and a clone attracts such users causing them to break contracts with the operator, there may be a case for Tortious interference with a contractual relationship. This would allow the original operator to sue the clone operator and obtain damages.

However, this theory is based on inducing users to break existing contracts. If the previous game is not in operation, and there are no current contracts, then such a suit would not be viable.

  • As a rebuttal to the last paragraph, see this answer on this site.
    – grovkin
    Feb 9, 2021 at 14:21
  • @grovkin that answer does not, in fact, address the issue at all. The question is not whether copyright has been abandoned (I think it cannot be under current US law), but whether there are current active contracts to be interfered with. That is a totyally different issue. Feb 9, 2021 at 14:45
  • "the issue" is too vague a phrase. The linked answer addresses the assertion you made in the last paragraph. There need not be an ongoing contract for the unlicensed use of the game client to violate copyright. If you think otherwise, try making the same argument about operating systems and such. Imagine a service custom designing its content to an operating system which can no longer be licensed and explaining to its users that all they have to do is pirate an old copy of the operating system and use it without a license in order to use the service.
    – grovkin
    Feb 10, 2021 at 6:41

Not an DMCA/Abandonware Exception 2021

I think what you're asking here is specific to abandonware exceptions. This is not an abandonware exception, the DMCA says

(B)The prohibition contained in subparagraph (A) shall not apply to persons who are users of a copyrighted work which is in a particular class of works, if such persons are, or are likely to be in the succeeding 3-year period, adversely affected by virtue of such prohibition in their ability to make noninfringing uses of that particular class of works under this title, as determined under subparagraph (C).

Subparagraph C defines who gets to determine a "noninfringing use",

(C) ... Librarian of Congress, upon the recommendation of the Register of Copyrights, who shall consult with the Assistant Secretary for Communications and Information of the Department of Commerce and report and comment on his or her views in making such recommendation, shall make the determination in a rulemaking proceeding for purposes of subparagraph (B) ...

The exceptions to the DMCA are determined by Librarian of Congress. The Librarian of Congress's latest recommendation can be found in "Federal Register / Vol. 86, No. 206 / Thursday, October 28, 2021 / Rules and Regulations 59627 ". In it, it explicitly says,

(17)(i) Video games in the form of computer programs embodied in physical or downloaded formats that have been lawfully acquired as complete games, when the copyright owner or its authorized representative has ceased to provide access to an external computer server necessary to facilitate an authentication process to enable gameplay, solely for the purpose of ... [purposes you're covered by].

In your case, they've "ceased to provide access", and you're covered in what you're trying to do: the problem is this exception is for "complete games" which is defined as,

video games that can be played by users without accessing or reproducing copyrightable content stored or previously stored on an external computer server.

Because this game has "copyrightable content stored on an external computer server" it's not covered by the exception. There are different rules for "eligible libraries, archives, or museums" but I don't see any reason to believe this would cover you.

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