Addy Osmani, who is involved in the development of Anthropic’s AI coding tool “Claude Code,” revealed on his X account on October 31 (Japan time) that he had added instructions to the tool directing it not to recreate specific existing games.The company stated that using Claude to infringe on intellectual property violates its terms of use, and it is expected that users will still be able to create original games and other content.
Instructions to Avoid Replicating Existing Games; Original Works “Expected to Continue Working”
On October 30 (Japan Time), X user chasm posted that a new rule had been added to Claude Code around October 27. According to the user, the rule is distributed from Anthropic’s servers via a flag named “tengu_heron_brook,” and there is no setting for users to disable it.The rule stipulates that while users may create original games, games in specific genres, or games using their own designs and assets, they must not recreate specific existing games—even if they change the name or claim the game is original.
In response, Addy Osmani explained in a reply to chasm’s post that he had added two sentences to the prompt for Claude Code running on Claude Opus 5.5 to guide it away from recreating specific games created by others.He stated that the system is expected to continue functioning as intended for original games, games within specific genres, and games created using users’ own designs and assets, and that he will continue making adjustments to strike the right balance. He also urged users to contact him directly if Claude refuses to generate content for which they hold the rights while these adjustments are being finalized.
AI-Generated Replicas of Existing Games Spark Debate; New Rules Draw Criticism
The trend of using AI to recreate or modify existing games had already been a topic of discussion even before these rules were introduced. In late September, posts on X could be found claiming to have recreated games like *Terraria* and *Rocket League* using Claude Opus 5.5.
Furthermore, concerns about AI-generated imitations are spreading among game developers. There have been reports of indie developers both in Japan and abroad receiving threatening emails from individuals claiming they would release AI-generated clone games first and demanding Steam items in exchange.
These new rules have drawn significant criticism and concern from users on social media and elsewhere.A prominent question being raised is, “While users are required to comply with copyright laws, how does Anthropic itself handle copyright in its own AI development?” Additionally, in a post, chasm raised the question of whether the rules might extend to affect related activities, such as game remakes and mod creation.
Osmani has stated that adjustments will continue, so the scope of the rules may change.
