Anthropic recently introduced a new system prompt aimed at preventing its Claude models from recreating specific, existing video games. Although this adjustment might protect the company from legal liability, it is expected to do little to halt the widespread trend of AI-assisted game copying and porting seen recently.
Discovery of the New Rules
A social media user and artificial intelligence decompilation enthusiast known as “chasm” first spotted the prompt modification, stating that a new regulation appeared in the Claude Code prompt around October 27. The rule, housed inside a JSON file named “tengu_heron_brook,” instructs the system to build original games and genre-based titles from user designs while prohibiting the recreation of specific existing games, regardless of whether they are renamed.
XDA independently verified the presence of this new directive in version 2.1.314 of the Claude Code binary released on October 30. XDA noted that the “tengu_heron_brook” identifier previously served different functions in earlier iterations, and that the Claude Opus 5.5 model featured separate, dedicated instructions within its system prompt bundle to restrict game replications.
Anthropic’s Response
Subsequent to the initial public findings, Anthropic software engineer Addy Osmani verified via social media that the organization integrated the new guidelines into the Claude Code prompt on Opus 5.5. He explained that the adjustment steers the model away from duplicating specific titles belonging to others because employing Claude to violate intellectual property rights violates company usage policies.
Osmani stated that the updated prompt still permits original games, genre-based projects, and developments utilizing personal designs and assets. Meanwhile, issue reports submitted on Anthropic’s GitHub indicate that the new restrictions are occasionally interfering with legitimate game development workflows.
