Anthropic updated Claude Code’s system prompt for Opus 5.5 to stop the model from recreating specific existing video games. The new rule, named ’tengu_heron_brook’, was active by October 30 and blocks clones even if they are renamed or passed off as original.
The change follows a flood of AI-powered projects unofficially porting well-known titles like Halo and GTA Vice City. Anthropic software engineer Addy Osmani confirmed the update, stating that using Claude to infringe intellectual property violates the service’s usage policy.
The restriction is designed to protect Anthropic from liability while acknowledging that users can switch to other models to bypass the rule. Developers building original games, genre titles, and projects with custom assets will not be affected by this specific change.
