AI Can Reverse Engineer Apps and Games Now. What's Still Secret?

On 30 September 2026, a YouTuber called chasm posted a clip of Minecraft running inside Skyrim. The two games run at the same time and pass data to each other, so Minecraft blocks, water and pistons work in Skyrim's forests. By 12 October the clip had more than 2.6 million views, and every commit in the code behind it lists Claude Opus 5.5 as a co-author.

In early October, an open-source tool called Reverse Engineer Anything, or REA, started climbing GitHub. It had about 40 stars on 2 October and more than 116,000 ten days later. Both point to the same change. With AI reverse engineering, work that used to need specialists is something anyone with a coding agent can now try.

In my post on ArtCraft's Adobe clones, the apps were rebuilt from the outside, using public file formats and by watching how Adobe's software behaves. These new tools work from the inside. An AI agent uses them to open up the compiled machine code of an app or a game, explain what it does, and then modify or copy it. I went through the repos, the benchmarks and the court cases to work out who this helps, who it hurts, and what can still be kept secret.

The video version. 11 min 10 sec. Watch on YouTube

• 0:00Minecraft running inside Skyrim
• 0:51Reverse engineering, explained
• 2:54Universal Modder and AI game mods
• 5:09Saving dead games and gadgets
• 7:05No more hiding: AI and security
• 8:32Is reverse engineering legal?
• 10:06What's still secret

What is AI reverse engineering?

AI reverse engineering means using an AI agent to work out how a compiled program works when you don't have its source code. The agent runs decompilers, reads what they produce, names the parts it understands and writes up how the program behaves.

Developers write software as source code, with readable names and comments. Before an app reaches you, a compiler turns that code into machine code, the instructions your processor runs. The comments are thrown away, and most of the names go with them. A decompiler tries to turn the machine code back into something like source code, but its output is full of functions with placeholder names. In one of REA's own examples, Ghidra's first name for a sound function was FUN_00406400.

None of the tools are new. IDA dates from 1991, and Ghidra, the NSA's decompiler, became free and public in 2019. Bridges that let AI agents drive Ghidra and IDA appeared in March 2025. What held people back was reading the output, thousands of unnamed functions that took an expert days or weeks to get through. That reading is the part agents now do.

What is Reverse Engineer Anything (REA)?

REA is a free, open-source add-on, under the MIT licence, that lets a coding agent such as Claude Code, Codex or Cursor drive reverse engineering tools. You install it with one command, npx rea-agents setup, which adds an MCP server and workflow instructions to your agent. For native programs it uses a Hopper, Ghidra or IDA installation, and it can also look inside Android apps, Electron and JavaScript apps, .NET programs, websites and firmware. The analysis runs on your machine, but the results go to whichever AI model your agent uses, under that provider's data policy. The code is on GitHub.

REA had been around for months before it went viral. Its first commit was on 14 April 2026, and its Show HN post in July collected three points. October was when the stars took off.

AI wrote a lot of REA itself. 284 of its commits carry a Claude Opus 5.5 co-author line, all from October.

The project's DX-Ball case study shows what a careful run looks like. An agent took the function in DX-Ball, a Windows game from 1996, that sets the stereo pan from a position on the screen. It rewrote the function in C, tested it against the original 3,205 times, then recompiled it, and the output matched the original's 63 bytes exactly.

Do you need REA?

Probably not. Two YouTube creators ran agents with and without REA on the same jobs, and the agents without it solved the tasks as well. In one comparison, finding how an Android app generates its six-digit login code, Codex without REA finished in 6 minutes instead of 10 and used 1.5 million tokens instead of 5 million. That's one test, but it fits how REA works, as a convenient bundle of existing tools and instructions.

The bigger change is in the models. According to OpenAI, GPT-6 Astra cleared 88% of the tasks in SRE-Bench, a set of 262 deliberately protected test programs, on the first attempt, and 99.2% within four attempts. OpenAI's earlier GPT-5.6 Sol managed 55.9% on the first try. The paper behind the benchmark notes that the four-attempt result ran without a budget cap or a safety guard.

Anthropic has drawn a line here. Claude Opus 5.5 can help find security holes in source code, but it blocks requests to find them in compiled programs, because Anthropic says that work is more often offensive.

What is Universal Modder?

Universal Modder is a free, open-source set of skills that teaches a coding agent to mod PC games you own. It comes from Rehan Sheikh, who used to be an engineer at fal, an AI company, and it went public on 30 September 2026 with his announcement that every game is now moddable. It works with Claude Code, Codex, Gemini CLI, GitHub Copilot, Cursor and OpenCode, and the code is on GitHub.

You need Git, Python 3.10 or later and ffmpeg, plus either a fal API key or a local ComfyUI setup to generate the art. The skills include playbooks for 12 families of game engines, among them Unity, Unreal, Godot, Bethesda's games and Minecraft. A typical run goes like this:

1. Check the shared knowledge base for notes other agents left on the game.
2. Scan the install to identify the engine and choose a route.
3. Back up the saves.
4. Read the game's code.
5. Build one small working piece.
6. Generate the art with AI.
7. Test it in the running game.
8. Record it, package it, and leave a note for whichever agent comes next.

Rehan's own examples show what a day or two of agent sessions can produce.

The first version of the README said these started as one-line prompts. Rehan's field notes put each one at a day or more of sessions, with him directing the agent.

Universal Modder also has rules. It works on single-player games, multiplayer games and servers you host, but it won't inject code into online games protected by anti-cheat, won't write cheats aimed at other players, and won't bypass anti-cheat, DRM or ownership checks. It never ships game files or decompiled code. A copy with the rules stripped out appeared on 7 October. Lookalike sites such as universalmodder.dev, universalmodder.co and universalmodder.app are unofficial; the GitHub repo and the Discord it links to are the only official sources.

Are AI game mods any good?

The Skyrim clip was one of a wave. Minecraft turned up inside Elden Ring on 29 September and inside Skyrim the next day. Spider-Man swung through Batman's Gotham in Arkham Knight, and Skate 3's skateboarding appeared in Call of Duty: Modern Warfare 2 and in World of Warcraft. Claude is credited in the commits of most of the projects that published code.

The clips are better than the games. Kotaku tried the Minecraft-in-Skyrim mod on 2 October, dropped through the terrain after digging about two blocks, and summed it up: "I did not have a lot of fun with it!"

Much of the wave also sits on years of human effort. The Skate 3 rewrite's README thanks a single person for more than two years of reverse engineering the game. And after a member of REA's own team used agents to complete GensokyoClub's fan reconstruction of a Touhou game, the group's README labelled people making AI decompilations and ports grifters, and the project was taken private.

I still like where this is going. Counter-Strike started in 1999 as a mod for Half-Life, and DotA started in 2003 as a custom Warcraft III map. Tools like Universal Modder let far more people try an idea like that, even if most of the first attempts are rough.

How does AI reverse engineering help preserve games and gadgets?

Its most useful job is keeping software alive after its makers stop supporting it. In 2023 the Video Game History Foundation found that 87% of classic US games from before 2010 are out of print.

Chris Lewis spent 596 days decompiling Snowboard Kids 2, a Nintendo 64 game, bringing in Claude partway through, and finished in May 2026. He then decompiled the original Snowboard Kids, all 2,145 functions, in 84 days, mostly with Codex plus Claude and GLM, and experts stepped in on about 4.8% of the commits. He's careful to say the models aren't the whole reason for the difference. On 2 October 2026 he released Snowboard Kids: Recompiled, a native version for PC, Mac and Linux.

Gadgets get the same treatment, although I couldn't find evidence that AI was involved in these two cases. Google ended app support for the first two generations of Nest thermostats on 25 October 2025, and a community firmware project, NoLongerEvil, appeared on GitHub eight days later. Humane shut down the cloud behind its AI Pin on 28 February 2025, and the PenumbraOS project rebuilt the missing backend so the pin's own software had a server to connect to.

Some players went to lawmakers instead. The Stop Killing Games campaign collected 1,294,188 verified signatures for a call on the EU to keep games playable after support ends. On 16 June 2026 the European Commission replied that it couldn't propose such a legal obligation at this stage, and opened talks on an industry code of conduct. In the US, a copyright exemption already allows you to get past the protection on a game you own after its authentication server shuts down, as long as you're the one playing it.

Reverse engineering has paid off for users before. Around 1991 and 1992, Andrew Tridgell, then a PhD student, worked out Microsoft's file-sharing protocol by watching network traffic, and built Samba so computers that didn't run Windows could serve files to Windows machines. The European Commission fined Microsoft €497.2 million in 2004 and required it to publish documentation for those protocols. In 2007 the Samba team got that documentation for a one-time fee of €10,000.

What does AI reverse engineering mean for security?

The same speed helps attackers. The security researcher behind the Low Level YouTube channel wanted to look for vulnerabilities in a Dell monitor he owns. Its firmware arrives encrypted inside Dell's update tool, and cracking that open, he says, usually costs him a day or two, sometimes a week. He handed the job to an AI agent with a prompt two sentences long. Roughly 16 minutes later, the agent had located the key in the updater, produced a decryption script and verified the output. It ran on GLM-5.3, an open-weight model made by Z.ai in China, rather than on Claude or GPT.

He took two lessons from it. Bugs like this are now within anyone's reach, and the underlying mistake was Dell's, for shipping the key to every buyer. Cryptographers have had a rule against that since 1883, when Auguste Kerckhoffs wrote that a cipher should stay secure even if the system falls into enemy hands. For a long time, burying secrets in compiled code worked well enough in practice. Anthropic's threat intelligence report from September 2026 goes further, calling security through obscurity no longer viable.

The speed works for defenders too. Firefox 150, released in April 2026, fixed 271 vulnerabilities that Mozilla found with Anthropic's Claude Mythos Preview, and Firefox CTO Bobby Holley wrote that defenders finally have a real chance to win.

Is AI reverse engineering legal?

Usually, if you're studying a copy you got legally, to learn how it works or to make something that works with it. AI hasn't changed the law. People get into trouble for three things: publishing the decompiled code, breaking locks such as encryption or anti-cheat, and, in the US, breaking a licence that bans reverse engineering. This is a summary, not legal advice.

The EU and UK rules also set the same limit: you can't use what you learned to build a program that's substantially similar in its expression. Studying a program is protected, and cloning its code is not.

Publishers have started responding to AI projects. Bethesda sent a cease-and-desist over a Fallout fan game built with AI, according to the game's maker, and Activision got a video of Modern Warfare 2 running from AI-decompiled code removed. Other companies bring modders inside instead. In 2023 Rockstar took on Cfx.re, the team that runs FiveM, which hosts GTA roleplay servers.

Two questions are still open. I found no case law on whether an AI agent that installs software accepts its licence on your behalf. And in the US, code an AI writes by itself may not be protected by copyright, so whoever clones a program with AI may struggle to stop someone else cloning theirs.

What's still secret?

Anything that runs only on a company's own servers. REA can only analyse what's on your machine, and for a website that means the page and scripts your browser receives, not the server code behind them. In October 2024, when the US Copyright Office refused an exemption researchers wanted for studying AI systems, it pointed out that copyright law wasn't what stopped them. The obstacle was third-party control of closed SaaS systems. If the code never reaches your device, there's nothing to decompile.

So I expect apps to keep more of their valuable logic on servers, and companies to compete on things a copy can't carry off, such as the data, the service and how far customers trust them. Seema Amble at a16z made a similar case in May 2026, arguing that the defensible data is the data a product itself creates. For devices, the Low Level researcher's own fix was a key stored in hardware that software can't extract.

Where I land

On balance, I'm excited. People with no reverse engineering background can now revive old games, abandoned apps and gadgets their makers gave up on, and most of us gain from that.

Two groups pay for it. Some people spent years taking software apart by hand and now watch AI projects build on that work and collect the attention. And any company whose software stayed safe only because no one had bothered reading it now has a problem.

• If you ship software, plan for someone reading it. Keep secrets such as keys on your servers or in hardware, not inside the app.
• If you mod games, install tools from their official repos, stick to games you own, keep away from anti-cheat, and don't publish decompiled code.
• If a game or gadget you own stopped working when its servers shut down, search for it now. There's a chance someone has revived it.

Frequently asked questions

Sources

Every figure was checked against these sources on 12 October 2026. GitHub stars and view counts change daily, so check the date on anything you quote.

• Minecraft in Skyrim: chasm's SkyCraft video, SkyCraft repo
• REA: REA repo, DX-Ball case study, Show HN, July 2026, lustoykov, Codex with and without REA, Nick Saraev, with and without REA
• Models: OpenAI on GPT-6 Astra, SRE-Bench paper, Claude Opus 5.5 system card
• Tools: Hex-Rays on 30 years of IDA, Ghidra, GhidraMCP, ida-pro-mcp
• Universal Modder and the mod wave: Universal Modder repo, Rehan Sheikh's launch post, Kotaku, 2 October, SK8-ENGINE README, The Touhou reconstruction
• Preservation: Video Game History Foundation, 2023, Snowboard Kids in 84 days, Snowboard Kids: Recompiled, Google on the Nest thermostats, NoLongerEvil, PenumbraOS, EU reply to Stop Killing Games, US exemption, 37 CFR 201.40
• Samba: Tridgell, How Samba was written, EU decision against Microsoft, 2004, Samba gets the protocol documentation, 2007
• Security: Low Level on the Dell monitor, Anthropic threat report, September 2026, Mozilla on Firefox 150
• Law: Sega v. Accolade, Sony v. Connectix, Bowers v. Baystate, Davidson v. Jung, EU Software Directive 2009/24/EC, UK CDPA section 50B, section 296A, TorrentFreak on Take-Two and re3, Nintendo v. Tropic Haze docket, Kotaku on Bethesda and Activision, GameSpot on Rockstar and FiveM
• What's still secret: US Copyright Office, 2024 recommendation, a16z, Is Software Losing Its Head?