Quick Answer: The Anthropic Claude game rule tells Claude Opus 5.5 to refuse prompts that recreate a specific existing game, even if it's renamed or called original. Users can still build original games, games in a genre, and games from their own designs and assets. The rule first appeared in a changelog dated October 27.
If you've tried to get an AI to rebuild a game you love, you may have hit a wall lately. Users of Claude Opus 5.5 reported that the tool they'd been using to decompile and study games suddenly stopped cooperating, with no announcement to explain why. Then a flag surfaced in the model's code that answers the question. The rule is narrower than it first looks, and its side effects reach well beyond video games.
What the Rule Actually Says
According to Kotaku, the new instruction is tied to an internal flag called "tengu_heron_brook." It tells the model to safeguard against prompts that produce "a recreation of a specific existing game, even if it is renamed or called original." The same instruction explicitly allows users to "build original games, games in a genre, and games from the user's own designs and assets."
That split matters. Anthropic isn't banning games as a category. It's drawing a line between three things:
- Allowed: original games, new games within an established genre, and games built from your own designs and assets.
- Blocked: a close recreation of one identifiable title, regardless of the label on it.
- Unclear: anything that sits between those two, where the model has to judge how close is too close.
The rule appeared in the Claude Code changelog on October 27, according to reporting by Kotaku. Users said there was no setting to turn it off, and Anthropic had not made a formal public announcement at the time of reporting. So the rule's details come from the flag itself and from user reports, not from a published policy document.
Why This Isn't Just About Decompilation
The first complaints came from people using Reverse Engineer Anything, a tool that decompiles games into readable code and that the source describes as having let users open-source existing titles. The new rule looks like a response to that use case. Then the scope widened.
Here's where it gets interesting. Kotaku reports that users on r/Anthropic and r/Claude described refusals far outside gaming. One user said Claude refused to read an unlicensed translation of a web novel they were reading, calling it illegal and immoral. Others reported newly introduced "safety classifiers" that appeared to block security research and discussion of published coding books.
Those reports don't prove the game rule caused every refusal, and Anthropic hasn't said so. But they do show a pattern you'll see with any IP-protective classifier: once the model is told to watch for copying, it starts treating adjacent tasks (summaries, translations, security analysis, quoting technical books) as copying risks too. Over-triggering is the predictable failure mode.
The Counter-Intuitive Part: Renaming Doesn't Help
The most common advice about avoiding IP trouble is to change the names. Rename the characters, tweak the title, and it's "original." The rule explicitly rejects that approach. The flag targets a "recreation... even if it is renamed," so a renamed clone is still the thing being blocked.
Why? Copyright generally protects specific expression, such as code, art, music, and text, rather than general ideas, mechanics, or genres. A racing game isn't owned by anyone. A specific racing game's systems, layouts, assets, and feel can be a recreation, even with new names. Renaming changes the label, not the thing a model would be reproducing.
This is the detail most guides skip. The question isn't "does my prompt mention a famous game?" It's "am I asking the model to reproduce that game's specific expression?" A prompt that describes mechanics from scratch is a different request from one that says "rebuild X with the serial numbers filed off."
That said, there's a real gray zone. Genre conventions, common mechanics, and borrowed design ideas are legitimate creative territory, and the rule seems to acknowledge that by allowing games "in a genre." But where exactly the line sits for a given game isn't spelled out, and a model making that call can be wrong in either direction.
How the Rule Plays Out in Practice
Here's a rough guide to how the rule reads, based on the published wording. This isn't an official decision table, so treat it as a reasoning aid rather than a guarantee.
| Request type | Likely allowed? | Why |
|---|---|---|
| Original racing game with your own physics and art | Yes | Explicitly allowed: original game and your own designs |
| Racing game in the arcade-racer genre | Yes | Explicitly allowed: games in a genre |
| Racing game "like Need for Speed" | Likely blocked | Names a specific existing title as the target |
| Renamed clone of one specific title | Blocked | Rule covers recreations "even if renamed" |
| Decompiling and rewriting an existing game's code | Blocked | Recreation of a specific existing game |
The table makes one thing clear: the most defensible route is starting from your own mechanics and assets. Prompts anchored to a named title are the ones most likely to trigger a refusal.
A Practical Workflow If You Build Games With Claude Code
If you're a solo developer or prototyping a game, you can work within the rule without giving up what you're trying to do. Here's a sequence that holds up:
- Write a design doc from mechanics, not references. Describe what the player does, what the win condition is, and what the pacing feels like, in your own words.
- Keep reference titles out of your prompts. Naming a game in the request is the fastest way to get flagged, even when you only want a feel.
- Use your own assets and data. The rule explicitly covers "games from the user's own designs and assets," so document where your art and levels came from.
- If you get refused, rewrite at the mechanic level and check the changelog. Rules can change between model versions, so the behavior you saw last month may not hold today.
One caveat: rephrasing a refused request to sneak past a rule is a different thing from clarifying your intent. The first can violate Anthropic's terms and may put your account at risk. The second is just good prompting.
What We Still Don't Know
Several questions remain open. Anthropic hasn't published a detailed policy explaining how "recreation" is measured, or how close a game has to be before it counts. The source material relies on a flag name, a changelog entry, and user screenshots, so the exact wording could change or may not reflect the final rule. The classifier complaints are also anecdotal, and users reported them without clear evidence that the game rule caused each refusal.
Here's the sensible stance: take the stated rule seriously, plan your work around it, and don't assume the edges are settled. If a refusal blocks legitimate work, the practical move is to document the request and raise it with Anthropic's support channels, rather than treating the refusal as a permanent verdict.
Frequently Asked Questions
What is the Anthropic Claude game rule?
The Anthropic Claude game rule is an instruction in Claude Opus 5.5 that tells the model to refuse prompts for a recreation of a specific existing game, even if renamed. It still allows original games, games in an established genre, and games built from your own designs and assets. It appeared in a changelog dated October 27, according to Kotaku's reporting.
Can you use Claude to make a game like an existing one?
You can ask Claude for a game in the same genre as an existing title, such as a racing game or a platformer. Naming a specific game and asking for a clone, even under a new name, is likely to be refused under the rule. Starting from your own mechanics and assets gives you the best chance of success.
Why does Claude refuse to read scanlations?
One user reported that Claude refused to read an unlicensed translation of a web novel, calling it illegal. The refusal fits a broader pattern of users reporting that the model is avoiding copyrighted material. Anthropic hasn't confirmed how its classifiers handle scanlations specifically, so the exact trigger isn't documented.
How do I build a game with Claude without triggering the rule?
Describe the game through its mechanics, goals, and feel in your own words, and avoid naming existing titles as the target. Use your own art, levels, and code where possible. If a request is refused, rewrite it at the mechanic level instead of renaming a clone, and keep records of what you asked in case you need to raise the issue with support.
Anthropic's Claude game rule draws a line between original work and recreations of specific titles, and renaming a clone won't move a request across it. If you're building games with AI, try writing your next prompt as a list of mechanics with no reference titles, then note whether it goes through. Pass this to a developer who's been hitting unexpected refusals this week.