Overview
- Anthropic quietly pushed the change to Claude Code around Oct. 27 and confirmed it on Oct. 30 when engineer Addy Osmani said two sentences were added to Opus 5.5 to steer Claude away from recreating someone else’s specific game.
- The new instruction tells Claude to build original games, genre‑style games, and projects using a user’s own assets but not to build a recreation of a specific existing game, even if a user renames it or calls it original.
- The rule is enforced as a server‑side system prompt (reported under the internal flag 'tengu_heron_brook') that makes Claude refuse disallowed requests and cannot be toggled by users.
- Developers and users report the change is already blocking some legitimate reverse‑engineering and development tasks, including creating digital modules and personal recreations of board games, and some teams have pulled public demos over clone fears.
- Experts say the prompt may reduce cloning on Claude and lower Anthropic’s legal risk but will not stop the larger wave of AI‑assisted ports and copycats because users can use other models, jailbreak safeguards, or alternative toolchains, and the move follows Anthropic’s past IP exposure, including a large class‑action settlement.