Claude Code gets prompt rule against recreating other people's specific games
Anthropic has confirmed that it added two sentences to the Claude Code prompt on Opus 5.5 to steer the coding tool away from rebuilding a specific existing game. Game Developer reports that an X user named Chasm spotted a rule pushed around October 27 and listed under the internal flag “tengu_heron_brook.” The text keeps original games, games in an existing genre, and games built from a user’s own designs and assets open, but blocks recreations of a specific game even when the project is renamed or presented as original.
Anthropic issued no standalone announcement. A spokesperson pointed Game Developer to a post on X by Addy Osmani, a member of its technical staff, who said the company wanted to keep the tool from infringing intellectual property because that breaks its usage policy. Osmani said original, genre and own-asset games should keep working, that Anthropic will keep adjusting the balance, and that developers whose legitimate games are refused should send those cases to him. Developers have since reported refusals on their own projects and on some basic reverse-engineering and troubleshooting tasks.
Madrobot reports that the text sits behind a setting called original_games_guidance, which Anthropic can switch on or off from its side, so users of other models may not receive it. Madrobot describes the rule as an instruction to the model rather than a technical block, which means enforcement depends on how a request is worded. Chasm reported that no user setting disables it, and Shane the Gamer notes that Anthropic has not explained how Claude separates a developer’s own project from a copy.
Why it matters
For companies selling coding agents, a prompt edit can change what the product will build without a changelog entry or announcement. Founders and operators who depend on Claude Code or similar tools should treat vendor prompts as moving parts. That means keeping a versioned record of the instructions their stack relies on, running regression tests against real workloads, and asking vendors what changed when output shifts. Investors should ask whether a portfolio company’s core workflow depends on behavior the vendor can alter at will.
The rule also marks a legal and product boundary that matters for game studios, tooling makers, and interoperability vendors. Work on reverse engineering or compatibility can look similar to cloning at the prompt level, so companies in these niches need an explicit policy for IP-sensitive requests and a test set of legitimate tasks. Anthropic has said developers can report wrongful refusals, which is a start, but teams should not rely on an informal channel for production work.
Key points
- 1Anthropic confirmed two sentences were added to the Claude Code prompt running on Opus 5.5.
- 2The rule was reportedly pushed around October 27 under the internal flag “tengu_heron_brook.”
- 3Original games, genre games, and games built from a user’s own designs and assets remain allowed.
- 4Recreations of a specific existing game are barred, even when renamed or presented as original.
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