Anthropic has updated its system instructions to prevent its Claude models from cloning specific, already-released video games, responding to a massive wave of AI-generated copies and retro game ports that has overwhelmed the developer community. Ars Technica reported that the company added two sentences to Claude Code’s prompt on Opus 5.5 to steer the software away from recreating existing intellectual property.
Anthropic Implements Strict Coding Rules Against Game Cloning
The new safety measure appeared in version 2.1.314 of the Claude Code binary, according to newmediafactor.com. A social media poster and AI decompilation enthusiast known as “chasm” first spotted the change in late October. The instruction sits inside a JSON file under the name “tengu_heron_brook”. The rule dictates that users can build original games, genre games, and projects from their own designs and assets, but explicitly prohibits building a recreation of a specific existing game even if developers rename or call it original.
If you're into game mashups, rewrites, decompiling, recompiling or emulating then my Discord is the place to be.https://t.co/lEaMb13tuZ
Addy Osmani noted that original games and genre titles are meant to keep working, adding that users can reach out directly if Claude turns down legitimate personal projects. The update arrives as AI coding tools drive a deluge of game clones and thousands of automated decompilation and porting projects. While these automated systems increase efficiency, veteran coders complain that vibe-coded ports fail to match human-centered quality standards.
Community Maintainers Shut Down Decomp.dev Amid AI Flood
Decomp.dev, a years-old hub dedicated to the difficult task of game decompilation, announced its closure in September. Community maintainer Luke Street explained that rapidly improving AI tools had broken the collaborative aspect of the platform. Newcomers rushed to port games using decompilations they did not contribute to, turning a gamified progress tracker into a hollow numbers game driven by token burning.
Street wrote that the platform was originally designed to keep human maintainers motivated when every fraction of a percent required painstaking effort.
Industry Observers Question Effectiveness of Model Restrictions
Despite Anthropic’s policy shift, industry analysts suggest the prompt change will do little to curb the wider AI copying boom. Eager game copiers can easily switch to other frontier models that lack similar restrictions. Furthermore, developers can utilize cheaper open-weight models that feature comparable capabilities while remaining entirely free of such system guardrails.
Frequently Asked Questions
When did the new Claude Code rule take effect?
XDA independently verified that the “tengu_heron_brook” rule appeared in version 2.1.314 of the Claude Code binary, which was released on October 30.
ANTHROPIC IS CRACKING DOWN ON VIDEO GAME REWRITES 🚨Claude Code picked up a new rule around Oct 27, sent from Anthropic’s servers under a flag called "tengu_heron_brook". There’s no setting to turn it off.The full rule: “Do build original games, games in a genre, and games… pic.twitter.com/0Zc5mQWHJt”
What specific instruction was added to the prompt?
The added rule states that users should build original games, genre games, and titles from their own designs and assets, but must not build a recreation of a specific existing game.
Why did the decomp.dev community platform shut down?
Community maintainer Luke Street announced the closure because fast-improving AI tools broke the collaborative nature of the platform as newcomers rushed to port games using unearned decompilations.
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