Anthropic confirms a Claude Code prompt change to stop Opus 5.5 recreating specific games

Anthropic has confirmed that it added two sentences to Claude Code's prompt on Opus 5.5 to steer the model away from recreating a specific existing game. Game Developer reported it on October 30.

An X user named Chasm had spotted the rule in Claude Code's rules, which they said was pushed on October 27 under the name "tengu_heron_brook". It 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." Chasm said the rule cannot be disabled; that is the user's claim.

An Anthropic spokesperson pointed Game Developer to a statement on X by Addy Osmani, an Anthropic member of technical staff: "We 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 our usage policy." Osmani added that original games, genre games and games built from a user's own designs and assets are meant to keep working, that Anthropic will keep iterating "to ensure we're striking the right balance", and invited users whose own work is refused to send it to them.

Game Developer says independent studios have grown worried about fast AI remakes of unreleased games, and that at least one studio cancelled a public playtest for that reason. It also notes that such limits can be sidestepped and that it is unclear how Claude would tell whether a user owns a game idea or its assets. Those are the outlet's observations.