Anthropic tells Claude Code to stop recreating existing games, while original and genre games stay allowed

A new rule in Claude Code

On Oct. 30, X user chasm wrote that Claude Code had picked up a new rule from Anthropic’s servers around Oct. 27. The rule arrives through a configuration field called “tengu_heron_brook.” According to chasm, there’s no setting to turn it off. As of Nov. 3, the post had more than 2.3 million views.

The full text chasm shared is two sentences long. The first tells Claude to build original games, games in a genre and games from the user’s own designs and assets. The second tells it not to build a recreation of a specific existing game, even if it is renamed or called original. In other words, the rule targets copies of specific games, not game development as a whole.

chasm@chasmmmmmmmmmmm

ANTHROPIC IS CRACKING DOWN ON VIDEO GAME REWRITES 🚨

Claude Code picked up a new rule around Oct 27, sent from Anthropic’s servers under a flag called "tengu_heron_brook". There’s no setting to turn it off.

The full rule: “Do build original games, games in a genre, and games from the user’s own designs and assets. Don’t build a recreation of a specific existing game, even if it is renamed or called original.”

Is this the end of game rewrites, modding and everything in between?

Anthropic: two sentences in the prompt

Anthropic’s Addy Osmani replied to chasm the same day. He said the company had added two sentences to Claude Code’s prompt on Opus 5.5 to steer it away from recreating someone else’s specific game. The reason he gave: using Claude to infringe IP is against Anthropic’s usage policy.

Osmani wrote that original games, genre games and games built from users’ own designs and assets are meant to keep working. He said Anthropic will keep iterating to strike the right balance, and asked developers to send him anything of theirs that Claude turns down. According to Game Developer, Anthropic answered its request for comment by pointing to this post.

Addy Osmani@addyosmani

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.

Original games, genre games, and games built from your own designs and assets are meant to keep working.

We'll continue to iterate to ensure we're striking the right balance. In the meantime, if Claude turns down something that's yours, send it my way.

How the rule is delivered

XDA found the rule’s text in the Claude Code 2.1.314 executable. In XDA’s assessment, tengu_heron_brook isn’t a game-specific flag but a general channel for remotely delivering system instructions; an earlier configuration used it for an unrelated note on reasoning effort. Accounts that get the rule this way have it applied to every model in Claude Code. A second path, “original_games_guidance,” delivers it to Opus 5.5 alone.

How widely the rule has been deployed, and whether it will stay, isn’t known. In XDA’s tests, Opus 5.5 and Opus 5 both initially refused to recreate Pokémon Diamond. Opus 5.5 did agree to help decompile the same game, which it distinguished from recreating it.

First came the Roblox clones

The rule followed a wave of clones on Roblox. On Oct. 14, Pandorio Games posted a video on X of Escape the Walls, its incremental game about punching through walls to escape. The video drew more than 5.6 million views. The earliest Roblox copies that could be found were live about 25 hours later. odinz, who published one of them, said Claude built the whole game; that is the creator’s own claim.

On Oct. 27, the copies moved on to big games. A near 1:1 copy of Counter-Strike 2 spread on Roblox, complete with the Dust 2 map, the knife and the round economy. Left 4 Dead 2 was ported to Roblox as Left 4 Survival 2. According to Dexerto, none of these copies had permission from the rights holders. That evening, KreekCraft said Roblox had deleted the ported games. The makers of these copies haven’t said they used AI; that’s an inference by streamers and commentators. Earlier in October, Activision had used a DMCA notice to take down AI-made browser ports of Call of Duty games.

Steam and indie studios

According to PC Gamer, Steam has been flooded for weeks with low-effort, vibe-coded games, many of them imitations or direct copies of existing titles. The most recent Steam Next Fest had twice as many demos as the previous one, with AI-assisted games accounting for most of the increase. At Steam’s Indie Connect event, Valve’s Tom Giardino said the company doesn’t want “to be gatekeepers telling developers which tools they should or shouldn’t use.”

According to Game Developer, several indie studios canceled public demos for fear that they would be cloned with AI. Moonlighter studio Digital Sun Games replaced the large public playtest it had announced for ReVamp with a smaller Discord test starting Oct. 29. It cited “recent news of games being reverse-engineered, cloned, and published before the original is even out.” Citing Polygon, Game Developer reported that Alliance Arts and Who’s You canceled the Steam Next Fest demo for Drunken Goddess Reflux.

Blocked work and open questions

Some developers say the rule also blocks legitimate work. On Oct. 30, the developer who runs Conflict Simulations LLC filed an issue in Claude Code’s GitHub repository. The company builds digital modules of board wargames, written from scratch, for clients who own the physical games. According to the report, Opus 5.5 sessions began refusing that work, citing the new instruction. The refusals started after the developer asked Claude whether the rule applied. The work isn’t licensed by the publishers. As of Nov. 3, no Anthropic response appears in the thread, and XDA hasn’t reproduced the refusals.

Game Developer wrote that the rule may stop only low-effort copycats, and that it’s unclear how software could tell whether an idea or its assets belong to the user. Commenters noted that determined copycats could switch to open-weight models. Reactions on X were split: tae kim called it a “good move,” while Token Gremlin called it bad news for Claude users who make games.