How Does Game Emulation Work and How Legal Is it?

Any retro-loving gamer knows it’s next to impossible to legally play most titles from the past 50 years of gaming history. This is where game emulators—essentially recreations of an old console’s hardware environment in software form—come into play. These open-source programs are some of the best and, for some, the only way to play the greatest titles of yesteryear. As easy as these emulators make the process for players, developers spend years finetuning their software, always all under the ire of game publishers who would prefer these software recreations not exist at all.

So, how do they work? Independent developers described it like you would a physical machine. Imagine you had a clock, every gear synced in perfect time. An emulator of that clock would take each output of the clock, every gear spinning, every switch flipped, and every clock hand ticked, and translate that into code.

Riley Testut, the main face behind the Delta emulator on iOS, chatted with Gizmodo about the rigors of development. Work on Delta is ongoing. Testut launched the first beta to bring online multiplayer to the Nintendo DS emulator earlier this month. It’s an exciting time for him and many others to test the limits of emulation on PC, handhelds, and even VR headsets. Still, he told us it took him close to five years to reach this point. Developing the base code of the emulator took relatively little time. Instead, the spit and polish required to make it playable required most of his and fellow developers’ effort.

He described the emulation process as akin to any video or image app. The data is just that—bits of code that need interpretation. An emulator takes ROMs (read-only memory), old games copied directly from old cartridges or discs, and then replicates the environment to play them.

“In my head, a ROM is just a JPG,” Testut said, relating these read-only files to digital image formats. “It’s just a piece of data, and then you have a picture viewer that reads the data and displays it. An emulator takes a piece of data and then just knows how to interpret that specific data into visual and audio.”

Longtime emulation creator Benjamin Stark, AKA Zodttd, most recently developed the Gamma emulator to play PS1 on iOS. He told Gizmodo over email that he likened emulation to a conversation between two machines.

“Imagine someone who couldn’t make it to a wedding party where they need to give a speech,” he said. “This person doesn’t speak the same language as the rest of the party. An emulator can be seen as an app that creates an AI avatar exactly like them. Their avatar socializes at the party, with everything said translated back and forth. Finally, their avatar reads a translated speech to everyone, as if the person were standing there.”

That’s the simple version, but it belies an incredibly complex web of scenarios that arise from translating hardware into a software environment. Emulating the relatively simple Game Boy is far less complicated than the PlayStation 2. The simplest form of this hardware-to-software is a kind of “interpretation,” when the emulation pretends to be a physical system. This would happen at “runtime” while the software operates. It’s more intensive, but it works fine for older systems like old Ataris or the NES running on something as powerful as a modern PC.

Emulators often get combined into packages for ease of use, as you might see on devices like the Miyoo Mini. For more modern devices, many users prefer the Steam Deck for emulation, and the reason for that is Emudeck. The person behind Emudeck, who goes by DragoonDorise online, isn’t an emulation developer per se, but he has a lot of experience getting these emulators to work on a unique system, that being the Linux-based SteamOS.

“Not all systems are designed the same at the hardware level,” Dragoondorise told Gizmodo over Discord. Something like the Sega Saturn is especially hard to emulate because of its number of processors. An emulator “has to mimic every one of those processors and the way they integrate and sync with one another. Black Magic.”

And then you get into the issues with peripherals. Stark said he had to do a lot of design to make the PlayStation’s first DualShock controller fit onto a touchscreen device. He said an emulator consists of a front-end alongside what he calls the “emulation core,” which displays all the game’s visuals, sound, and menus. The user only interacts with the front-end, and the difficulty is getting it as seamless as possible.

For something with 3D graphics, it gets far more complicated. A Gamecube emulator like Dolphin isn’t just pretending to be Nintendo’s famed, and often overlooked console with a handlebar, it’s “recompiling the ROM on the fly into a native executable,” Testut said. That’s something your average PC has a lot easier time running than if it were trying to do it at runtime. The difficulty could be getting a modern device to comprehend the 3D graphics. Stark said that, on mobile, developers commonly use programs like OpenGL, Metal, or Vulkan to write 3D graphics for these systems. Depending on the platform, you may be developing more for one than another.

“You have a whole embedded compiler that’s constantly compiling code and making it look good, and the performance improvement is drastic,” the Delta developer said. “That’s a huge step up in complexity, but that’s what gets to the modern systems today.”

Just How Big is Emulation?

Some consoles are harder to emulate than others. Most notoriously, emulated games for the Nintendo 64 may show broken textures or effects that ruin the experience. That’s why there’s a burgeoning world of FPGA emulation, which is essentially a form of hardware replication that can play old games in their original format.

While it offers verisimilitude to the original console experience, FPGA is often a far more expensive option for most consumers, which is why software emulation still reigns supreme. According to Testut, there may be several hundred emulation developers with big enough names to have a following. Stark said some developers will develop the “core” of the emulation, allowing others to build off it and create the front-end. Beyond that, thousands more independent actors are likely offering time and code for these individual projects. DragoonDorise related it to a FOSS—a Free and Open Source Software—development “utopia.”

There are a few legends in emulation development. Stark mentioned the developer Exophase, who created multiple emulation cores and front-ends, such as the GameBoy Advance emulator goSP. He contributed to that project and helped bring it to the iPhone long before Apple started allowing emulators on iOS.

It’s easy to underestimate how big emulation is online. However, if you peek at the Emulation Wiki, you’ll find lists of emulators for every console under the sun, even those in a niche such as Mattel’s Intellivision or Nokia’s N-Gage. Then, there’s the huge and growing homebrew scene. These are developers making games for these old consoles, selling the ROMs, and even manufacturing cartridges capable of being played on emulators, original consoles, or an FPGA device. For some examples, look to Goodboy Galaxy for the Game Boy or Alwa’s Awakening for the NES.

Even though they may detest the idea of ROMs, relating it to piracy, modern publishers rely on emulation. Current-day retro-focused companies like Digital Eclipse make their living by creating “interactive documentaries” of past games. The company effectively builds emulations of those games by looking at and recreating the game’s actual ROM. Xbox confirms on its support page it uses emulation for all the titles from Xbox 360 and the original Xbox you can play on Game Pass. The only difference between these companies and an open-source emulation is the developers and publishers own or pay for the rights to these titles.

Those lucky games that get official emulator release are the exception, not the rule. In some cases, older games are caught up in license hell. A game made in the ’70s, ’80s, or ’90s might have an ownership split between the original developers or defunct companies, and few modern companies want that headache of deciphering that mess for the sake of rereleasing an old game. Take, for example, Goldeneye 007, whose rights were split between Xbox, Nintendo, Rare, Metro-Goldwyn-Mayer, Eon Productions, and Danjaq LLC. That game only got a rerelease in 2023, despite its enduring popularity.

The passion, instead, comes from those who originally played these games. The industry is full of developers who got started by emulating or enhancing older titles. Seth Fulkerson, a designer at the indie studio Limited Run Games, cut his teeth by remastering the infamous CD-i Nintendo-licensed games Link: The Faces of Evil and Zelda: The Wand of Gamelon. Last year, Fulkerson and his studio released Arzette: the Jewel of Faramore, a game heavily inspired by those 1993 titles, even including the awkward, computer-made animations.

When I recently met up with Rob Dunlavey – the illustrator who did backgrounds for the Zelda CD-i games & Arzette – he gave me an incredibly heartfelt gift…the original world map sketches for both games. I’m so happy and unbelievably grateful. pic.twitter.com/vrvRTCxab1

— Seth Fulkerson (@thedopster) April 3, 2024

Simply put, the games industry is inherently tied to emulation, not just for the sake of older games or re-releases but also for new titles. The issue is that there’s still no legal precedent to speak to the legality of emulation in all its many contexts. Inevitably, that’s bound to cause issues.

Are Emulators Legal?

Many of the largest publishers and console makers have demonized emulation for years. Distribution platforms like Nintendo Online, Xbox Game Pass, or PlayStation Store all offer mere licenses to games and never the games themselves. What should happen when those online stores go defunct, like what happened with the Wii U, 3DS, and Xbox Live marketplaces? You won’t be able to buy those games again until those owners re-release them later, if they ever do.

One of the earliest examples of emulation, Connectix’s Video Game Station, which allowed users to play PlayStation games on Mac back in 1999, managed to fight off a lawsuit from Sony. The game company eventually bought VGS, just to make sure it could shut it down. Despite this early legal win, game companies—especially Nintendo—have long-held enmity for emulation.

Last year, Nintendo blocked Gamecube and Wii emulator Dolphin from coming to Steam. There was a lot of initial consternation on Nintendo’s part over the development team using a Wii Common Key to get around the console’s inherent encryption. After talking to an attorney, the Dolphin developers wrote that they wanted to clarify: “Dolphin is not primarily designed or produced for the purpose of circumventing protection” but is solely designed to recreate the Gamecube and Wii as software. They argued that “only an incredibly tiny portion” of the code was used to get around encryption. Plus, developers pointed out Dolphin is capable of playing homebrews as well.

Derek Bambauer, a professor at the University of Florida Levin College of Law and an intellectual property expert, told Gizmodo in a phone interview that the encryption key cited by Nintendo likely wasn’t enough to claim copyright under the Digital Millennium Copyright Act. As long as the developers aren’t hacking the system to any “clean room” extent, then they have a better chance of arguing in court that their emulator isn’t designed to facilitate piracy. Dolphin previously said all it took to extract the key was “some smart engineers and a pair of tweezers.”

“They have written a different set of source code that can accomplish the same set as functions that Nintendo or some other console does,” Bambauer said. “I think it would be very tricky to argue that it’s copyrightable because all they copied is the higher level stuff.”

Since the start of 2024, there has been blood in the water drawn out from emulators, and Nintendo is the biggest shark prowling these depths. In March, James games company managed to shut down the Yuzu Switch emulator after it filed a lawsuit against its developers. The developers also agreed to pay $2.4 million for the settlement. In the following months, the owners of the Mario franchise then went after many other mirrors of Yuzu and other Switch emulators like Pineapple. On Oct. 1, Nintendo pressured the developers of the Switch emulator Ryujinx to shut down operations.

Jonathan Loiterman, an attorney with the Foundation Law Group who focuses on gaming and digital media, told Gizmodo over the phone that companies like Nintendo could target emulators if they wanted to. Even the threat of a protracted court battle is enough to make a small-fry independent emulation developer drop their work, as was the case with Yuzu and other Switch emulation developers. In other cases, with emulators of past consoles, it’s simply not worth Nintendo’s time to do so, not to mention the community backlash it may cause.

“Nintendo has deep pockets, they have the money to do it,” Loiterman said. “Instead, they are enforcing what are reasonable boundaries for what is OK. [Nintendo doesn’t] have a commercial opportunity in the Gamecube today in the way they do for the Switch.”

Even showing emulation working online can put you in Nintendo’s crosshairs. Russ Crandell, who runs the excellent Retro Game Corps YouTube channel, is one more DMCA strike away from seeing the streaming site take down his channel. He said Nintendo targeted videos of him playing a Switch emulator and even another video showing Wii U emulation working well on Android. He told The Verge that several of those videos show he physically owns the games he’s emulating on camera.

While most console emulator developers might feel safe for now, that doesn’t mean companies’ priorities won’t change in the future. Beyond that, ROMs are a potential legal minefield. Companies could go after ROM distributors like movie and music companies did in the 2000s against piracy. That hasn’t happened to any significant degree. Loiterman said Nintendo could legally try to “expunge the Earth of all the NES emulators out there,” but that may not actually help the company’s long-term goals.

In Yuzu’s case, Nintendo went after those developers over “facilitating this community of people who were exchanging ROMs,” Loiterman said. Still, as both Loiterman and Bambauer pointed out, Nintendo’s case was focused on how Yuzu worked to defy a technological measure meant to keep copyright safe, something that’s restricted in Code 1201 of the Digital Millennium Copyright Act. Practically all major modern consoles have encryption built into the system, something emulators must somehow bypass to recreate the hardware as software.

Designers aren’t too worried about their legal future. Stark and Testut pointed out that Yuzu had to bypass a lot of encryption on the Switch.

“The emulation community is the core market of video game companies, centered around nostalgia,” Stark said. “Emulation is seen as an act of love by the community for these companies.”

Beyond all that, users should feel safe downloading an emulator. These hardware-to-software environments are fair game so long as they don’t contain any ROMs themselves. However, the games themselves, those ROMs, are direct copies of the original games. They are breaking copyright, and it is certainly illegal to distribute. That means any system that comes with pirated ROMs preinstalled is similarly illegal. Emulation developers are better off trying to ensure they promote how their emulators can also play homebrews and non-pirated content, according to Bambauer. It’s not close to a full legal shield, but it establishes these programs exist for uses beyond piracy.

Emulators Are More Than Ethical; They’re Integral for Games Preservation

Books fall apart. VHS tapes eventually degrade. DVDs will scratch and die, but our society has done a much better job at preserving movies and literature than we have with gaming. Part of that is how games are tied to their original format and individual consoles. Video game preservationists have cited emulation as one of the few ways our society has been able to preserve the art form. That’s important because a Video Game History Foundation study found that 87% of games from before 2010 are not commercially available anywhere.

In 2019, former games journalist Frank Cifaldi—now the founder and co-director of the VGHF—said during the annual Games Developer Conference that the state of video game preservation is “dire.” To maintain access to out-of-print games, he said emulation is “the best tool for keeping older games in print in a cost-effective and accurate way.”

 

In 2018, Sony released the PlayStation Classic console that used the PCSX emulator in its hardware. The console didn’t sell as well as it should have, mostly due to UI issues, but it was one of the first times major publishers recognized the benefits of emulation. Though Atari has released backward-compatible consoles for the 2600 and 7800, few major game makers have gone the same route. Though few publishers want to give emulators tacit approval and sell their old ROMs for a profit, they seem to use emulation internally. Recently, one fan at the Nintendo Museum in Japan heard a chime when they disconnected a controller playing the SNES. That sound indicated the machine was likely running Windows, which would point to the game running on an emulator.

@BobWulff pic.twitter.com/6HjWqN4DRH

— Chris (@ChrisMack32) October 14, 2024

The video game industry refuses to acknowledge the potential of emulation. In October, the U.S. Copyright Office sided with industry groups representing the games industry against preservationists. The office decided to continue enforcing rules restricting video game museums and libraries from allowing people to access defunct games online remotely. Part of the Copyright Office’s register’s issue was over the concept of “emulation as a service” that was put forward by preservationists. The office’s director, Shira Perlmutter, wrote that emulation “would implicate copyright owners’ distribution rights.”

In response, the VGHF wrote the decision “forces researchers to explore extra-legal methods to access the vast majority of out-of-print video games that are otherwise unavailable.” If you want to research and analyze many old, defunct games, you have no choice but to download ROMs.

Testut said he hopes that there may come a day when emulators are seen as far more legitimate. Companies may sell consumers the ROMs of their old games for a few bucks a pop, then let them play however and wherever they want. That seems like a pipe dream for the vertically integrated publishers and console manufacturers, but one can dream.

The fact that emulators have to exist points to an existential failure of the games industry to preserve its most beloved titles. Emulator developers spend years creating and perfecting their software. Some emulators are slightly janky to use, but others, like Delta, Dolphin, or PS1 emulator Gamma, make the process of playing relatively seamless. The community is strong and growing all the time. As much as the license holders say they’re trying to expand the classics market, they’ve obviously failed to meet demand.

There is still no official English translation of the classic RPG Mother 3, but there are enduring fan translations that have become the defacto way to play the game in the U.S. and elsewhere. Even when you ignore the classics, emulation still makes a case against companies that try to exploit customers. There is demand for Super Mario Sunshine for the Gamecube. In all its wisdom, Nintendo released a special version of past 3D Mario games in Super Mario 3D All-Stars, but in a limited run that now costs an obscene $140 on Amazon. Should the legacy Japanese game maker truly be surprised if more consumers turn to emulation, especially to experience these games as close to how the studio originally intended?

“Emotionally, [emulation is] a way of going back to the golden age of video games,” DragoonDorise said. “Morally, it’s the only way to make sure those video games are not lost to time.”