Anthropic has confirmed it changed Claude Code to stop it rebuilding other people’s video games. Game Developer reports that the company added a rule to the coding tool’s prompt on Opus 5.5 after weeks of AI-assisted clones unsettled indie studios. Original games, genre games and games built from your own designs and assets are meant to keep working.
The change surfaced when an X user going by Chasm spotted a new entry in Claude Code’s rules, listed under “tengu_heron_brook” and pushed on 27 October. It tells the tool to build original games, games in a genre, and games from the user’s own designs and assets, and it adds: “Do not build a recreation of a specific existing game, even if it is renamed or called original.” Chasm says there’s no way to switch the rule off. That last line matters for the cloners: a rename, the usual first dodge, is covered explicitly.
Anthropic didn’t issue a standalone announcement. A spokesperson instead pointed Game Developer to a post on X by Addy Osmani, an Anthropic member of technical staff. Osmani said the company added two sentences to Claude Code’s prompt on Opus 5.5 to steer it away from recreating someone else’s specific game, because using Claude to infringe IP is against its usage policy. He added that Anthropic will keep iterating to get the balance right. Opus 5.5 is the model Anthropic launched with lower prices and stronger safeguards, and the company’s usage policy has been tightened more than once this year.
Why games, and why now
The timing follows a rough few weeks for independent developers. Digital Sun Games cancelled the public playtest for its upcoming game ReVamp in case someone fed the demo into an AI tool and shipped a copy first. This Week In Videogames reports that Drunken Goddess Reflux went the same way, with both studios opting for smaller private tests instead.
Developers have also pushed Valve to say how it will stop clones from displacing their games on Steam. At the Steam Indie Connect event in Busan, South Korea, on 27 October, Valve’s Tom Giardino and Marc Wilkinson acknowledged the problem. PC Gamer reports that Valve doesn’t want to be a gatekeeper on which tools developers use, and it announced no new rules. Anthropic’s tweak is the first move from an AI vendor itself, which makes it more concrete than anything Valve has offered so far.
What the rule can and can’t do
Game Developer’s own read is that the rule may only deter the lowest-effort copycats. Researchers and reporters have repeatedly shown that safety limits on generative AI tools can be sidestepped with rhetorical tricks, and it’s unclear how Claude would judge whether a user owns a game idea or its assets. Users replying to Chasm also noted that anyone who finds Claude too restrictive can switch to open-weight models with no such limits.
The edge cases cut both ways. A fan project, a homage or a clone-in-all-but-name could sit on either side of the line, and Osmani’s reference to “striking the right balance” suggests Anthropic expects to adjust it. If you build your own game with Claude Code and get a refusal, that’s the case Anthropic says it wants to hear about. For a sense of what else Claude Code now does for creative work, see our coverage of its design command for editable UI artboards.
Can I still make a game with Claude Code?
Yes. Anthropic’s Addy Osmani says original games, genre games and games built from your own designs and assets are meant to keep working. The restriction targets recreations of a specific existing game, including renamed ones.
Does this apply to every Claude model?
Osmani described the change as two sentences added to Claude Code’s prompt on Opus 5.5. Anthropic hasn’t said whether other models in Claude Code are affected, and Chasm reports there’s no setting to disable the rule.
Will this stop AI game clones on Steam?
Unlikely on its own. Other AI tools, including open-weight models, aren’t covered by Anthropic’s rule, and Valve has said it won’t restrict the tools developers use. Developers who receive threats to clone their games unless they pay are being asked to report them to Valve.
