Claude Code Blocks Game Clones: What the Opus 5.5 Rule Means

Anthropic has added a rule to Claude Code telling Opus 5.5 not to build recreations of specific existing video games, and the company has confirmed it. Original games, genre games and games made from your own assets are meant to keep working. Developers are already reporting some false refusals, so here is what is confirmed and what is still unclear.

Quick summary

• The rule is two sentences added to Claude Code's prompt for Opus 5.5, first spotted around October 27 by X user Chasm.
• Anthropic's Addy Osmani confirmed it, saying using Claude to infringe IP is against the usage policy.
• It is not confirmed to apply to every Claude model or to the Claude chat apps.
• Some developers say legitimate projects and reverse-engineering tasks were refused.

What does the new Claude rule say?

As quoted by Game Developer and PC Gamer, the instruction reads: "Do build original games, games in a genre, and games from the user's own designs and assets. Do not build a recreation of a specific existing game, even if it is renamed or called original." It was reportedly delivered through a server-side setting named "tengu_heron_brook", and XDA Developers says it independently found the text in Claude Code version 2.1.314. XDA also notes that the mechanism has been used for unrelated instructions, so it is a general way of pushing prompt changes rather than a game-only switch.

Has Anthropic confirmed it?

Yes. Engadget reports that Addy Osmani, a member of Anthropic's technical staff, said the company added two sentences to Claude Code's prompt on Opus 5.5 to steer it away from recreating someone else's game, and that Anthropic will keep iterating to get the balance right. An Anthropic spokesperson pointed Game Developer to that post rather than issuing a separate statement. Anthropic has not said the same rule applies to other models or products.

Why now? The AI game-clone problem

The change lands after weeks of alarm in the indie scene. Fans have used AI tools to rebuild browser versions of games such as Halo: Combat Evolved and Grand Theft Auto V, and some small studios have pulled public demos for fear of AI copycats beating them to market. Steam has also been flooded with low-effort releases, and itch.io says daily game-page creation doubled in two months; see our itch.io AI slop report.

Who is affected, and what still works?

Real-world results are mixed. Tom's Hardware reported users saying non-malicious reverse-engineering and troubleshooting tasks were blocked. One independent test (AI Parabellum) ran nine prompts on two Claude Code versions and saw no outright refusals, which suggests the behaviour is inconsistent. Treat third-party tests as indicative only; they were not run by Anthropic.

What does this mean for modders and indie developers?

Modding and decompilation are not named in the rule, and XDA notes it does not explicitly ban decompilation or static recompilation. The practical risk is a vague refusal, especially if you cannot easily show that assets are your own. Game builders should keep records of their assets. Indie teams worried about clones get some comfort, but a prompt rule is not a legal protection, and other tools have no such limit.

Related reading

For more on AI shaking up the industry, see how Anthropic's IPO filing describes its business, and browse our launch calendar for new games.

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