An AI-generated Fallout fan game set in New York has been taken offline after its creator said Bethesda parent company ZeniMax Media sent a cease-and-desist notice over the project.

The experiment quickly went viral, with its original demonstration attracting millions of views on X. It also arrived during a sudden wave of AI-assisted game decompilations, mash-ups and recreations that has divided traditional modding communities.

What Was the Fallout New York AI Game?

First unveiled Fallout: New York on Sept. 28, describing it as a complete Fallout game playable through a web browser and built with Claude Opus 5.5. The project included quests, dialogue trees, V.A.T.S., S.P.E.C.I.A.L., terminals, lockpicking and a working Pip-Boy, alongside familiar Fallout companies and products such as Vault-Tec and Nuka-Cola.

As such, the game contained no downloaded texture, model, music or sound files. First confirmed in a Patreon post that its environments, characters, billboards, sound effects and other assets were generated through code at runtime.

The scale was surprisingly large for something produced in several days. First said the New York map contained 117 locations, 112 named characters and 46 weapons, with locations including Central Park, the Empire State Building, Madison Square Garden, the Brooklyn Bridge and Federal Reserve Bank.

Underneath that content was an AI-assisted development pipeline rather than a single prompt. First described Claude as the project’s lead developer, with specialist agents assigned to building modules, reviewing screenshots, finding problems, revising code and verifying the results.

The process reportedly involved roughly 580 agent runs across 20 workflows, with as many as 12 operating simultaneously. First said the finished project contained close to 300,000 lines of JavaScript and could be distributed as a single HTML file.

Its Fallout similarities were deliberate rather than incidental. In his detailed breakdown of the project, First said his original request wasn’t for something merely inspired by Fallout: “I wanted it to be exactly like Fallout: the Pip-Boy, V.A.T.S., S.P.E.C.I.A.L., terminals, bobby pins, the radio, the landmarks. And I wanted billboards for all the Fallout brands you’d expect in a city this loud.”

Why Did ZeniMax Target Fallout New York?

Even before the game disappeared, First acknowledged that Bethesda might object to the project. He stressed that Fallout: New York was completely free and that he wasn’t making money from it, calling the project a technical demonstration created because he loved Fallout. He even joked about adding a quest where the player had to serve somebody legal papers while the target repeatedly ran away.

A few days later, that joke became considerably more relevant.

First posted what he described as a cease-and-desist notice from ZeniMax Media and subsequently took Fallout: New York offline. The publicly shared document hasn’t been independently authenticated, and Bethesda hasn’t publicly detailed the dispute itself, so the action is best described as a legal notice that First says came from ZeniMax.

According to reporting on the document, ZeniMax objected to the fallout.nyc domain and use of Fallout intellectual property. The notice reportedly argued that the domain incorporated the Fallout trademark while the website contained copyrighted material associated with ZeniMax’s games.

First responded by asking Bethesda to “make a Fallout game instead so I don’t have to,” before apologizing to people who had played his version.

Whether a project is free doesn’t automatically remove intellectual property concerns. Fallout: New York used the Fallout name alongside recognizable terminology, branding and systems, making the dispute substantially specific, compared to asking an AI model to generate a post-apocalyptic RPG.

That also separates it from conventional fan mods Bethesda has previously allowed to exist, including ambitious projects such as Fallout: London. Those generally require players to own an existing game and operate within an established modding ecosystem rather than presenting themselves as standalone Fallout games through their own branded domain.

AI Game Mods and Mash-Ups Are Rapidly Spreading

Fallout: New York isn’t an isolated experiment. Claude Opus 5.5, which Anthropic released Sept. 22, has triggered a wave of developers and AI enthusiasts experimenting with game code, decompilation and automated modding.

Recent social media demonstrations have combined Minecraft with Elden Ring, Skate 3 with Call of Duty: Modern Warfare 2, Escape from Tarkov with Skyrim, Portal with Call of Duty Zombies and Super Mario 64 with Dark Souls.

Some of these projects use Claude to decompile two games and run them simultaneously, synchronizing actions while visually placing elements from one game over another. The result can make it appear that Minecraft’s Steve is firing a bow inside Elden Ring, for example, even though the character hasn’t literally been imported into the other game’s code.

The trend has generated significant backlash from established modders. Some have warned that automatically generated projects could flood communities with low-quality modifications whose creators don’t fully understand the underlying code.

Kingdom Hearts modder Discount Mods suggested they might stop making mods entirely if AI-generated projects became the dominant form of community content. Developer Kran, who openly uses AI during some modding work, similarly criticized the mash-up trend while arguing that AI itself still has legitimate potential for mod development.

The debate extends to decompilation and native PC ports. Developers involved with established recompilation projects have objected to AI being applied to years of human research and tooling, particularly when automated projects are then presented alongside or in competition with their work.

Claude Opus 5.5 has also already been used for direct game recreation. In late September, AI engineer Rehan Sheikh used the model to create a working recreation of Terraria overnight, describing the experiment as evidence that “all games are open source now.” He later clarified that he wouldn’t release or monetize it following criticism over using AI to reproduce a game that remains commercially available.

The Last Word

AI-assisted modding and game creation is moving significantly faster than the legal, ethical and cultural debates surrounding it. Claude Opus 5.5 has already been used to recreate games, accelerate decompilation and produce increasingly elaborate cross-game mash-ups only weeks after launch.

Fallout: New York shows both sides of that acceleration particularly clearly: AI helped one person coordinate a project containing hundreds of thousands of lines of code in roughly five days, but it also allowed that experiment to reach obvious intellectual property conflicts almost immediately. Whether these tools ultimately strengthen traditional modding or undermine it may depend less on what AI can technically reproduce than where creators decide the boundaries should be.

Featured Image Credit

Image via Steam