Around Oct 27, users noticed Claude Code receiving a new server-side rule (flag name tengu_heron_brook): build original games, games in a genre, and games from the user's own designs and assets, but do not build a recreation of a specific existing game, even if it is renamed or called original. The post that surfaced it drew about 8,700 likes and nearly 2 million views on Oct 30. The same day, Addy Osmani, who works on Claude Code at Anthropic, confirmed on X that the team added two sentences to Claude Code's prompt on Opus 5.5 because using Claude to infringe IP is against Anthropic's usage policy. He said original games, genre games, and games built from your own designs and assets should keep working, that the team will keep iterating, and that users can send him wrongly refused requests.
Key Takeaways
- ✓Scope: the change is just 2 sentences in Claude Code's system prompt for Opus 5.5, pushed from the server with no user-side toggle (Addy Osmani's post)
- ✓Rule text (per the flag tengu_heron_brook users captured): original games, genre games, and games from the user's own designs and assets are allowed; a recreation of a specific existing game is not, "even if it is renamed or called original" (original report, about 8,700 likes and nearly 2M views)
- ✓Basis: Anthropic's Usage Policy prohibits using its products to infringe, misappropriate, or violate a third party's intellectual property rights
- ✓Feedback path: Osmani says the team will keep tuning the line and asked users to send him wrongly refused requests; there is no separate Anthropic blog post yet, and benchmarks do not apply
Key Decision Metrics at a Glance
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Project Links & Resources
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Background and pain point
"Rebuilding" a famous game in a few hours with a coding agent is a common demo on social media, but it runs straight into third-party game IP. Around Oct 27, users found that Claude Code had quietly picked up a new server-side rule, sparking a debate over whether Anthropic is overreaching.
Architecture
This is not a retrained model or a new filter. Two sentences were added to Claude Code's system prompt for Opus 5.5 and delivered through a server-side flag (the name users captured is tengu_heron_brook), so it took effect without a client update and there is no setting to turn it off. In Addy Osmani's words, it "steers" the model away from recreating a specific existing game; the model still judges each request in context, so the line will be fuzzy at the edges.
Benchmarks
This is a product policy change, so there are no benchmarks. The verifiable numbers are that the prompt change is 2 sentences (Osmani's words), the original report drew about 8,700 likes and nearly 2 million views, and Osmani's confirmation drew about 86,000 views and 200+ replies. Anthropic has not published refusal-rate data.
Getting started
Original games, genre games (for example "make a roguelike"), and games built from designs and assets you own should keep working. If you are rewriting, porting, or modding a game you own and get refused, state the ownership of the designs and assets in your prompt and, as Osmani invited, send him the case. Recreating a third-party game can infringe IP, which the Usage Policy already prohibits.
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Discussion & Comments
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