Anthropic Tells Claude AI to Stop Remaking Existing Video Games

Anthropic Deploys Tengu Heron Brook Prompt Flag Against Claude Game Clones

An undisclosed update pushed on October 27 delivered a hardcoded rule to Claude Code that explicitly bans the recreation of specific existing video games, according to user reports on X. Game Developer reported that the restriction, delivered under the server-side flag “tengu_heron_brook,” states that users can build original titles or genre projects, but cannot reproduce named games even if they are renamed or rebranded.

The update arrives amid an industry-wide surge of AI-driven game remakes and decompilations that have flooded the market over recent months. YouTuber chasmmmmmmmmmmm shared this update on Twitter. Many independent developers have previously attributed these rapid ports to Anthropic’s Claude Opus 5.5 model, which debuted on September 22.

Addy Osmani Confirms Prompt Changes to Prevent IP Infringement

Addy Osmani, a member of technical staff at Anthropic, confirmed the adjustment in a post on X cited by Game Developer, explaining that two sentences were added to prompt instructions for Opus 5.5. Osmani stated that the measure aims to steer developers away from intellectual property infringement while preserving the ability to build original games and genre-based projects using personal assets. “We added two sentences to Claude Code’s prompt on Opus 5.5 to steer it away from recreating someone else’s specific game because using Claude to infringe IP is against our usage policy,” Osmani wrote.

Kotaku reported that users across Reddit and social platforms previously noticed a stealthy nerf to Opus 5.5’s reverse-engineering capabilities around October 21, with safety guardrails interrupting prompt sequences mid-sentence. In one example, Claude stated that a safety check stopped [its] response partway through and that it could no longer produce that write-up again, even reworded. However, several users in the thread have disputed this.

Developer Fallout And Ongoing Industry Pressures

Independent studios have grown increasingly alarmed by fast-follow AI remakes threatening to beat original demos to market. Digital Sun Games canceled its public playtest for the upcoming game ReVamp out of fear that participants might ingest the demo into an AI tool to generate competing clones.

Game Developer noted that safety filters can frequently be bypassed using rhetorical phrasing, and automated software lacks a reliable mechanism to verify whether a user legally owns a specific game concept or asset library. Users discussing the restriction on social media warned that developers seeking unrestricted code can simply migrate to open-weight models lacking similar governance rules.

Frequently Asked Questions About The Claude Code Restriction

Can users disable the tengu_heron_brook rule in Claude Code?

No setting exists within Claude Code to turn off the restriction. The rule is pushed directly from Anthropic’s servers via remote system prompt injection. Chasm reports that there is no way to disable the rule.

Which AI model is primarily associated with the recent wave of game decompilations?

Users and outlets have largely attributed the surge of vibe-coded game ports to Anthropic’s Claude Opus 5.5 model, which was released on September 22.

How does Anthropic’s official policy distinguish allowed projects from prohibited ones?

According to Addy Osmani’s statement, Claude is permitted to build original games, genre-specific titles, and projects derived from a user’s own designs and assets, but cannot recreate specific existing intellectual property.

More on this story: Valve Rejects AI Gatekeeper Role Amid Steam Game Cloning Concerns · MIT Researchers Find Claude Opus 4.7 Agents Play in Virtual World