Claude Code will build you a game, but no longer a copy of someone else’s

Claude Code, Anthropic‘s AI coding agent, now turns down requests to rebuild a specific video game that already exists. The instruction it follows is blunt: build original games, games in a genre and games from the user’s own designs and assets, but do not build a recreation of a specific existing game, “even if it is renamed or called original.”

For anyone making games with AI, the line is easy to state and harder to apply. A roguelike deckbuilder inspired by Balatro should still get built. A line-by-line rebuild of Balatro with a new logo should not. And because the rule sits in Anthropic’s own instructions to the model, users have no setting to switch it off.

The rule was spotted by an X user who goes by Chasm in Claude Code’s internal list of rules, under the label “tengu_heron_brook.” Anthropic did not publish an announcement. When Game Developer asked, a spokesperson pointed to a post by Addy Osmani, a member of Anthropic’s 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 your own designs and assets are meant to keep working,” and that the company will keep adjusting the rule to strike the right balance. He also asked developers whose own projects get refused to send them to him, according to PC Gamer.

The rule arrives after weeks of complaints from indie developers who say their games and demos have been copied with the help of AI. Digital Sun, the studio behind Moonlighter, cancelled the public playtest of its next game, ReVamp, rather than risk someone feeding the demo into an AI tool and shipping a clone first. PC Gamer reports that the latest Steam Next Fest showed twice as many demos as the previous edition, with AI-assisted games making up most of the increase.

Valve has acknowledged the problem without promising a fix. At its Steam Indie Connect event in Busan, Valve’s Tom Giardino said the company does not want “to be gatekeepers telling developers which tools they should or shouldn’t use,” and advised developers to keep adding features and personality that are hard to copy.

Two sentences in a prompt are a modest barrier. Game Developer points out that safety limits on generative AI tools have repeatedly been talked around with rhetorical tricks, and that it is unclear how Claude can tell whether a user actually owns a game idea or its assets. Osmani’s statement covers Claude Code on Opus 5.5, and Anthropic has not said whether other models or the regular Claude chat app follow the same rule. Anyone determined to clone a game can also switch to open-weight models that run on their own hardware with no such restrictions.

The change applies wherever Claude Code is used, since it lives in Anthropic’s instructions to the model rather than in any regional setting. Chasm reported the rule on October 30, saying it had been pushed on October 27, and Osmani confirmed it the same week. Anthropic has been fighting copyright claims on several fronts: last year it agreed to a $1.5 billion settlement with authors who said their books were used to train its models, and owners of Elvis Presley‘s song catalog have since sued the company over his songs.

For small studios, the rule changes the default rather than the odds. Copying a game with Anthropic’s agent now takes a deliberate workaround, and the clones will keep coming from tools that never added the two sentences.

Tags: Anthropic, Claude, Elvis Presley, video games, Steam, Claude Code, AI coding tools, Valve