Anthropic Adds Game‑Copying Guardrails to Claude, but the AI Cloning Wave Persists

Anthropic’s New Prompt Targets Game Cloning

Last week Anthropic rolled out a fresh system prompt for its Claude models aimed at preventing the AI from reproducing specific, existing video games. The change is intended to reduce potential intellectual‑property liability for the company.

A social‑media user known as “chasm,” who follows AI decompilation, first flagged the alteration. According to chasm, a new rule was added to the Claude Code prompt around October 27 and is stored in a json file called tengu_heron_brook. The rule reads:

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.

XDA later confirmed that the rule appears in version 2.1.314 of the Claude Code binary, which was released on October 30. XDA also noted that the same rule had been repurposed in earlier versions and that the Claude Opus 5.5 model carries its own distinct instructions restricting game recreations.

Anthropic Confirms the Update

Following chasm’s report, Anthropic software engineer Addy Osmani posted on social media that 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 because using Claude to infringe IP is against our usage policy.”

Osmani emphasized that the prompt still permits “original games, genre games, and games built from your own designs and assets.” He also invited users whose projects are blocked to reach out to him.

Quote from Osmani (October 30, 2026):

“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.”

The Growing Tide of AI‑Assisted Game Copying

Anthropic’s move arrives amid a surge of AI‑driven game projects that repurpose existing titles. Developers are using AI coding tools to create quick demos that mimic popular games, prompting some creators to hesitate before sharing early builds publicly.

At the same time, thousands of AI‑powered decompilation and porting efforts for retro games are underway. What once required painstaking human labor can now be accomplished orders of magnitude more efficiently, though veteran coders argue that many AI‑generated ports fall short of the quality of human‑crafted versions.

Community Fallout: decomp.dev Shuts Down

The decompilation community felt the impact directly. Decomp.dev, a long‑standing forum dedicated to the “brutally difficult, time‑consuming task” of game decompilation, announced its closure last month.

Maintainer Luke Street explained that rapid advances in AI tools had “broken” the community aspect, as newcomers race to port games using decompilations they did not contribute to. He described the shift from a motivating “progress bar” to a “hollow numbers game” driven by token spending and superficial porting goals.

Will Anthropic’s Guardrails Make a Difference?

While the new prompt represents a “noble effort” to curb AI‑generated copying, its effectiveness is uncertain. Eager copiers can simply migrate to other frontier models that lack similar restrictions, or to cheaper open‑weight models that remain competitive in capability.

Even if the broader AI industry adopted comparable bans, developers could still opt for unrestricted alternatives, limiting the overall impact of Anthropic’s policy change.

In short, Anthropic has taken a concrete step to protect game IP within its own ecosystem, but the relentless tide of AI‑assisted cloning shows no sign of abating.