Anthropic adds rule to stop Claude Code recreating existing games

Anthropic has modified its AI coding assistant, Claude Code, to prevent it from generating clones of existing video games. The change was implemented on October 27 and was first noticed by X user Chasm, who shared details about the internal rule named 'tengu_heron_brook.' The update instructs the model to focus on original creations, genre-based games, or projects using user-owned designs and assets, explicitly excluding recreations of specific existing games, even if renamed or rebranded.

The restriction cannot be disabled by users, according to Chasm’s observations. Anthropic’s member of technical staff, Addy Osmani, later confirmed the update on X, stating that the company added two sentences to Claude Code’s prompt for Opus 5.5 to prevent IP infringement. Osmani emphasized that original games, genre-based projects, and user-designed assets would remain unaffected, while reiterating the company’s commitment to refining the balance of these safeguards.

Despite the update, the effectiveness of the rule remains uncertain. Game Developer highlights that AI model restrictions can often be bypassed with carefully crafted prompts, and there is no clear method for Claude Code to verify whether a user owns the rights to the designs or assets they are using in their projects.

The change reflects growing industry concerns about AI tools being misused to clone games. Recent examples include Digital Sun delaying a public playtest of ReVamp due to fears its demo could be exploited by AI systems, while Valve has faced pressure to address how AI-generated clones might overwhelm Steam with non-original content.