Let's say I want to publish a NES game and I've written the game and it's in .nes ROM format (I haven't, but let's pretend hypothetically). And I want this software to run on modern platforms like iOS / macOS / Android / Nintendo Switch / Steam / Playstation / etc. So I write a wrapper app/virtual machine/emulator (pick the term you like) that serves to run the ROM and also enable some networked multiplayer functionality and so forth.

Will Nintendo most likely litigate because I used their proprietary (albeit retro/dated/discontinued) format?

And if legal issues are likely to crop up, is it best to (A) contact Nintendo directly to work out some sort of licensing deal or (B) just make some other 8-bit format that is very similar to (but just different enough from) the NES format?

From a retro gaming purist standpoint, certainly the look/sound/feel of the original NES format would be preferred over a format designed to recreate or approximate it.

I understand that when I phrase a question as "will... most likely...?" it invites opinion-based answers. But even opinion-based answers would be appreciated because this question is based on a hypothetical scenario that has not happened. If someone could answer, for example: "You're screwed because Nintendo can sue you based on x premise." or "You can probably do this safely because of yada-yada clause in blah-blah law..." that would still be helpful and I would accept it as an answer.

Note: There is a question similar to mine, and the answer is essentially "they'll probably sue you if you're making money from it". But I'm not really satisfied with that, so I'm forming a slightly more detailed and more comprehensive question.

It is possible Nintendo has released some kind of official statement (and possibly even a licensing program) regarding this matter that I am just not aware of. In that case a link to this in the answer would be appreciated.

Also, should we take into consideration that if the game is published for Nintendo's current console (Switch), that Nintendo would stand to gain some profit from the release anyway and be less likely to complain about the intricacies of what technologies were utilized in the game's creation?

Furthermore, modern games are usually made with a game engine such as Unreal Engine or Unity, and a license fee is usually owed to the creators of the engine by the game developers. The .nes format is not exactly the product of a game engine, but more like the product of low-level machine code. Sure, there are authoring tools like NESmaker that might sort of fall under the category of "game engine"... not really sure. And when you consider how low-level the coding for the NES is, it's not even clear to what extent the ownership of that technology can really be attributed to Nintendo. It may be the case that any .nes file I create is entirely mine, in the same way that any .psd file I make using Photoshop belongs to me (not Adobe). But this kind of software law stuff is obviously not my area of expertise, which is why I am asking here.

Finally, would releasing the .nes file for free possibly lessen the likelihood of becoming a target for litigation based on the premise that anyone can "steal" my game and run it on an emulator, but what customers are paying for with the app is essentially the convenience of running that file on their hardware of choice?

This is mostly a question out of curiosity, but as someone who appreciates retro games and is considering dabbling in game dev, I would like to know. Thanks.

Edit: Come to think of it, there are titles such as Namco Museum being released on Switch and obviously were originally written for NES, so wrapping NES games for a modern console is a current practice. Whether Namco had to pay anything extra to Nintendo to release this title is anyone's guess. It is also possible in Namco's case that they had some existing license deal established from when they first released the games decades ago.

Related links:

Is It Legal To Develop Homebrew NES Games?

Why people are still making NES games

  • Oracle v. Google might be relevant.
    – Someone
    Aug 24, 2022 at 4:58
  • 1
    What is an NES game? What is Famicom? What is "wrapping a game"? What is ".news ROM format"? The question is so buried in technical jargon that it is hard to discern what the underlying legal issues presented are. Also, try to focus on one question at a time rather than a whole host of related questions.
    – ohwilleke
    Aug 24, 2022 at 5:18
  • @ohwilleke If you are not qualified to answer the question, just ignore it. Software law is a thing (hence the existence of a "software" tag here), and there are people whose job it is to understand such "jargon". Legal matters can sometimes also be technical matters - even if that's not convenient for you. I don't feel that I unnecessarily complicated the issue, and the terminology I used in my question was for the purpose of being specific about exactly what I meant. The question is somewhat specialized, but that doesn't mean it should be dismissed. There is no better SE sub-site for this.
    – Mentalist
    Aug 24, 2022 at 5:29
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    @Mentalist The questions and answer remain part of SE indefinitely, so one needs to clarify abbreviations and to explain what you are saying so that when concepts that are current cease to be that they can be understood.. Software law also isn't actually a thing. There is copyright law and licensing law dealing with software. Yet cases are decided by non-specialist judges under non-specialist legal code. Also, "Will Nintendo most likely litigate" also calls for specific legal advice not general concepts, & licensing plus infringement is too much for one question..
    – ohwilleke
    Aug 24, 2022 at 5:37
  • @ohwilleke I have added links to clarify some of the terminology.
    – Mentalist
    Aug 24, 2022 at 5:51

1 Answer 1


Emulators are legal. They've been legal since courts ruled in favor of Bleem!, a commercial PlayStation emulator, in the 90s (though the company that made it still went out of business thanks to the lawsuit). Furthermore, Micro Mages, an NES game developed in the modern age that received a physical cartridge release, is currently available on Steam and itch.io as a packaged emulator version. All three releases additionally come with a standalone copy of the game ROM that can be played in an emulator of your choice. There is also nothing illegal about making a game not licensed by Nintendo for such consoles (most famously done by the Christian game developer Wisdom Tree); in fact, Micro Mages is not licensed by Nintendo either. Such games cannot use Nintendo trademarks, of course, but the only actions Nintendo has historically been able to take against distributors of such games otherwise is to stop doing or refuse to do business with them.

Note the parody of the Nintendo Seal of Quality on the Micro Mages box art: Micro Mages box art with parody of the Nintendo Quality Seal)

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