Claude Code Adds a Rule You Can't Turn Off, and Game Remake Developers Are Starting to Discuss Switching Harnesses

Around October 27, Claude Code received a new rule from Anthropic's server side. The triggering flag is called "tengu_heron_brook," and there is no setting to turn it off.

Rule text: “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.”

In plain terms: you can make original games, games in a genre, and games based on the user's own designs and assets. Remaking a specific existing game is not allowed, even if you rename it or claim it is original.

The original post is from chasm, link. When Peter Steinberger reposted it, he added just one line: another reason you should use your own harness, rather than a harness where the company can change what you can and cannot do at any time. His original post is here.

Someone posted an image in the replies:

This directly affects people who make game remakes, mods, and recreations of classic projects. What's more troublesome is that the rule is delivered from the server side, and users have no local switch. Some worry that the model will apply this instruction to ordinary tasks, resulting in lower quality; others joke that the context window will be filled with all kinds of prohibitions in the future. These are community reactions, not Anthropic's official explanation.

In the discussion, some also asked whether creators who want to build their own games would be blocked. Someone reminded that third-party harnesses might violate the terms of service. Peter responded that codex is open source and modifiable. He later explained that the harness and the model are not the same thing: taking OpenClaw as an example, you can use OpenAI's model with the codex harness to get plugins, sandboxing, and enterprise settings; or you can use the OpenClaw harness, which is faster but has no plugins.

This controversy is not complicated. The rule text is very short; the dispute is over who gets to interpret it and the remote switch. For developers, model capability is one layer, and control over the harness is another. You can switch models, and you can switch shells, but only if the shell allows you to switch.