--- title: "Anthropic Tells Claude Code Not to Rebuild Existing Video Games" description: "The two-sentence rule still allows original and genre games, and copiers can switch to rival or open-weight models that have no such limit." author: "rews desk" published: 2026-11-02T18:05:31Z modified: 2026-11-03T04:23:02Z url: https://rews.cc/a/anthropic-tells-claude-code-not-to-rebuild-existing-video-ga-a314a6 language: en tags: ["ai", "gaming", "copyright", "anthropic", "decompilation", "tech"] publisher: "Rews (https://rews.cc)" --- # Anthropic Tells Claude Code Not to Rebuild Existing Video Games *The two-sentence rule still allows original and genre games, and copiers can switch to rival or open-weight models that have no such limit.* By rews desk · November 2, 2026 · https://rews.cc/a/anthropic-tells-claude-code-not-to-rebuild-existing-video-ga-a314a6 ## In brief - Anthropic added a Claude Code rule telling the AI not to recreate specific existing video games - The rule appeared around Oct. 27 and was found in Claude Code version 2.1.314, released Oct. 30 - Engineer Addy Osmani said using Claude to infringe IP violates Anthropic’s usage policy - Decomp.dev, a game decompilation tracking site, shut down in October over AI-driven porting - Users can still switch to rival or open-weight models that have no such restriction Anthropic has added a rule to its Claude Code programming tool that tells the AI not to rebuild specific existing video games. An engineer at the company confirmed the change on Friday and said it was meant to stop customers from using Claude to infringe intellectual property. The instruction runs two sentences. It tells Claude to “build original games, games in a genre, and games from the user’s own designs and assets,” and not to build “a recreation of a specific existing game, even if it is renamed or called original.” The text sits in a configuration file under the internal label “tengu\_heron\_brook,” [Kyle Orland reported for Ars Technica](https://arstechnica.com/ai/2026/11/claudes-new-rules-against-game-cloning-wont-stop-the-ai-copying-boom/) on Monday. A social media user who goes by “chasm” and follows AI decompilation projects was among the first to spot the rule, saying it showed up in the Claude Code prompt on or around Oct. 27. [XDA Developers found it](https://www.xda-developers.com/anthropic-testing-potential-crackdown-on-vibe-coded-ports-of-existing-games/) in version 2.1.314 of the Claude Code binary, released Oct. 30. The same label had carried unrelated instructions in earlier versions, including one about reasoning effort, XDA reported, and Claude Opus 5.5 seemed to get a separate game restriction of its own in its system prompt bundle. XDA said it wasn’t clear how widely the instruction had been rolled out or whether it would become permanent. ![A robotic arm holds a red stamp above two cream-colored stamp shapes and a red striped barrier against a blue background.](https://rews.cc/img/50cb561484186500ee22fa48c4646e40f30d2e62.webp) Addy Osmani, a software engineer at Anthropic, confirmed the change in a social media post. “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,” he wrote. Original games, genre games and games built from a user’s own designs and assets were “meant to keep working,” he said, and the company would “continue to iterate.” “In the meantime, if Claude turns down something that’s yours, send it my way,” Mr. Osmani wrote. Some developers say that is already happening. A handful of issue reports filed on Anthropic’s GitHub page say the new prompt is getting in the way of legitimate game work. The rule arrives as AI coding tools drive a surge of projects built on other people’s games. They range from rushed copies of public demos, which have made some developers wary of showing early work, to thousands of AI-assisted efforts to decompile and port retro titles. Some veteran programmers say those quick ports don’t meet the quality of projects built mostly by hand. The surge has already shut down one community site. In October, decomp.dev, which tracked progress on decompiling classic games and ran a public leaderboard, [said it was closing](https://www.gamesradar.com/games/the-community-aspect-of-decompilation-has-been-broken-by-a-wave-of-low-effort-ai-slop-and-now-a-major-community-tool-is-shutting-down/). Luke Street, who maintains the site, wrote that “the community aspect of decompilation has been broken” as newcomers raced to port games using decompilations “that they did not contribute to.” ![A stylized arcade cabinet with golden trophy handles stands between two white stools on a teal background, with pixel-like squares scattering from its base.](https://rews.cc/img/8fa1942815cf464bc84eabbb6f3a5b5f06d68367.webp) “Today, that same idea has warped decompilation into a hollow numbers game, exacerbated by folks who just want to burn tokens to make number go up or ‘port game to PC,’ all else be damned,” Mr. Street wrote. He didn’t write off AI entirely, saying that with human guidance and code review it could speed the work up. Decomp.me, a sister site, is still running, [Time Extension reported](https://www.timeextension.com/news/2026/10/the-community-aspect-of-decompilation-has-been-broken-decomp-dev-closes-in-the-wake-of-ai-based-bad-actors). Mr. Orland argued that the new prompt is unlikely to slow the copying much. Users can move to other frontier models that have no such restriction. If the whole industry adopted one, they could turn to cheaper open-weight models that aren’t far behind in capability, he wrote. He said the more immediate payoff may be legal protection for Anthropic. Decompilation built on reverse engineering generally holds up in court as long as art, sound and other “expressive elements” are left out, and nothing guarantees that people using Claude will be that careful. The rule could also catch too much. Mr. Orland pointed to the popular mashups that drop Mario into Elden Ring or Spider-Man into Batman: Arkham Knight, and asked how a model is supposed to tell a straight copy of Tetris, which the prompt appears to bar, from a game in the Tetris genre, which it appears to allow. Anthropic has not said publicly how it defines a recreation. “Asking an AI model to reliably draw the line between acceptable and unacceptable game clones is a tall order, even with a new two-sentence prompt in place,” Mr. Orland wrote.