What Is Game Decompilation, and Why Is AI Breaking It?

Decompiling a game used to take a group of fans years, and the slowness turned out to be part of the value. AI has taken much of it out, and in the middle of October the person running one of the scene’s biggest tracking sites switched off its public leaderboard because of what came next.

That site’s closing statement is the best explanation of this whole mess so far, partly because it isn’t really anti-AI. To see why, you need three words that keep getting used as if they mean the same thing.

Decomp, recomp and port are different jobs

Decompilation starts from the fact that a finished game is machine code, which a processor can read and a person mostly can’t. A decomp rebuilds readable source code from that. The serious version is called matching decompilation, where the rebuilt code has to compile back into the same machine code as the original. The tracker’s statement puts that work “on the scale of years” for any moderately sized game, even with a number of people contributing. The Verge points to the original Animal Crossing on GameCube as one that took a group years.

Recompilation skips most of that. It translates machine code into native code for a new machine, often with AI tools now. It’s much quicker, though VGC reports that some believe the results are harder to mod.

A port is just the game running somewhere it wasn’t built for. A decomp can lead to one, but it isn’t one. Banjo-Kazooie shows the order: fans reverse-engineered the N64 game into readable code in 2024, and an unofficial PC port came out of that work this year.

These projects are all unofficial, and nothing here tells you where to find them.

A dark grey Nintendo 64 console with a grey controller plugged into it. Image: Evan-Amos, Public domain.

What changed in 2026

According to the statement, people had tried AI on this for years with mixed results. Models released early this year did better, and they appeared to know the community’s specific tools without being told. They still needed a lot of human cleanup, and they could cheat, producing code that compiled to the right result but could never pass as what the original developers wrote. They were expensive for what you got too.

Newer models went further. The statement says they follow complex directions better, stay on track through long tasks, and are “exceptionally good permuters”, meaning they write small scripts that try many versions of the code until one matches. They do all that faster and cheaper than the models before them.

The Verge reported on the 23rd of October that projects like these have been going viral at a rapid rate, with Halo in a browser and Wind Waker on an iPhone among them. Chris Sotraidis, an AI consultant who makes ports as a hobby, told the site that working without AI would have been “extremely slow by comparison”.

The complaint isn’t about the tools

The statement says plainly that AI “can expedite the decompilation process in a significant way”. Its problem is with how the speed gets used, and it lists three things.

The first is what it calls “hostile forks”, where someone copies a project that’s still in progress and finishes it with AI, whether or not the team wanted that. Some projects refuse AI for legal or ethical reasons, and others accept it but don’t want low-effort contributions from strangers.

The second is the race to port. The statement argues that porting is relatively easy compared to decompiling, so people who did none of the work can rush out what it calls a “half-baked, barely-functional port” from someone else’s decomp.

The third is language. Decompilation was meant to be research into how these games work, and now “decomp” gets used to mean “PC port”.

The clearest example came on the 1st of October, from DarioSamo, who led the Banjo-Kazooie PC port. In a statement on X, the developer said a new Banjo-Tooie recomp was “NOT associated with us” and “entirely AI-generated”, and that taking the team’s research and throwing AI at it was “very disrespectful”. That’s the developer’s description of how the recomp was made, and I couldn’t verify it independently. The Banjo team has been open about wanting to do Tooie itself in time, and said it wasn’t “interested in engaging a race to the bottom”.

So the leaderboard went. It was built to motivate people when every fraction of a percent took real effort, and the statement says it had become “a hollow numbers game”. The main index and new submissions are off, while existing project pages stay up.

The site didn’t ban AI, and the reasoning there is the most human part of the whole thing. Slop is hard to define and harder to moderate, and one hobbyist had no wish to rule on hundreds of projects. Not everyone agrees with the call. PCMag noted Reddit users accusing the site of gatekeeping.

What a fast port leaves behind

A port gets you a game you can play. A proper decomp gets you an explanation of the game, and that’s the part I think is worth protecting. The Verge makes the same point: if a tool does the work, nobody learns why the original programmers did what they did, and that knowledge is what lets you restore a game faithfully instead of only keeping it running.

There’s an honest case on the other side. Some old games can’t be bought any more, and something rough that runs beats something perfect that never arrives. Sotraidis expects a lot of what’s called slop today to improve with better tools, but added that better tools “aren’t automatically going to make people give proper credit”. That’s the right worry. The tools don’t care who did the research they’re standing on, so the people using them have to.

Xbox has noticed all this as well. Asha Sharma’s memo on the 13th of October called easier access and new life for old games “unmistakably good outcomes for players”, and it’s right about the players. Nothing in it deals with who gets credit, which is the argument the scene is actually having.

Whether it’s legal depends on who you ask

It depends on the project and the country. VGC describes decompilations as technically legal because the developers don’t use leaked content or copyrighted assets, and players supply their own copy of the game. That’s a press description and not a court’s finding.

Take-Two took a different view in 2021 when it sued the people behind reverse-engineered versions of GTA III and Vice City, claiming the aim was to create and distribute pirated versions. The four named developers denied infringement and cited fair use. The claims against them were dismissed in April 2023 after a settlement in principle, so the case ended without a ruling on that question.

PCMag expects many of the new browser ports to attract copyright complaints, since so many lack approval from publishers. A slow scene of hobbyists working on old games was easy to leave alone. Viral ports of famous ones are harder to ignore.

The code nobody gets to fork

The tracker’s statement finishes with a small FAQ, and one answer is better than anything else in it. Can you fork the site and host your own? No. Its repository has never had an open source licence, and the author reserves all rights to the “(entirely human written)” code.