Anthropic has added instructions intended to steer Claude Code away from recreating specific existing video games. The change draws a line between direct copies and original games, but it arrives as AI-assisted porting and copying spreads across tools and communities.
What Claude’s new instructions say
A social media user known as “chasm” noticed a prompt change late last week, saying a new rule appeared on or around October 27. The rule says Claude should build original games, games in a genre, and games based on a user’s own designs and assets, but should not recreate a specific existing game, even if it is renamed or described as original.
XDA later independently verified that the rule appeared in version 2.1.314 of the Claude Code binary, released on October 30. XDA also reported that the rule name, “tengu_heron_brook,” had served other purposes in earlier versions, and that Claude Opus 5.5 appeared to have separate instructions against game recreations in its system prompt bundle.
Anthropic software engineer Addy Osmani confirmed 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.” He said original games, genre games, and projects made from a user’s own designs and assets should still work. He also said Anthropic would keep adjusting the instructions, after a handful of GitHub issue reports suggested the prompt was interfering with some game development work.
AI tools are changing the pace of copying
The new restriction comes amid a surge in AI-assisted projects based on existing games. Some developers have become reluctant to show early demos publicly because they fear others will quickly copy them. At the same time, thousands of AI-powered decompilation and porting projects for retro games have appeared.
These tasks once demanded painstaking human effort and considerable time. AI tools have made the work much more efficient, although veteran coders argue that some “vibe-coded” ports and decompilation projects do not meet the quality of human-centered efforts.
The change has affected communities built around the work itself. Decomp.dev, a long-running community focused on the difficult, time-consuming task of game decompilation, announced it was shutting down last month. Maintainer Luke Street said quickly improving AI tools had broken the community aspect, with newcomers racing to port games, sometimes using decompilations they had not contributed to.
Street described a shift in what had once been a motivating shared effort: progress tracking, which had helped people persist through slow, incremental work, had become a hollow numbers game for people eager to spend tokens and get a game ported, regardless of the process.
A prompt cannot control every model
Anthropic’s rule may discourage some direct recreation within Claude, but it cannot stop users from turning to other frontier models without the same restriction. If the wider AI industry adopted similar limits, users could still choose cheaper open-weight models that are not subject to those controls and are not far behind in capability.
The prompt could nevertheless serve Anthropic’s interests by showing that the company is trying to prevent its tools from being used for infringement. The article notes that AI companies can face legal problems when models generate images based on copyrighted works. Anthropic’s policy statement gives the company a way to explain its position, though a prompt alone cannot ensure users follow it.
Decompilation based on reverse engineering code can generally pass legal muster when expressive elements such as art and sound assets are excluded. But a person using Claude to create a project may not carefully keep those elements out, even with a warning in place.
Where does a clone end and a new game begin?
The instruction also leaves an unsettled creative boundary. A direct recreation of a specific game is meant to be blocked, while a game in the same genre is meant to be allowed. Yet deciding whether a project is one or the other can be difficult.
Mashups raise another question. The source points to projects that combine different game concepts, such as adding Mario to Elden Ring or Spider-Man to Batman: Arkham Knight. They may be understood as transformative works, but they can also involve protected characters and images. The prompt does not explain how Claude should handle that distinction.
Even a familiar genre can sit close to a specific title: the article asks how a model should distinguish a recreation of Tetris from a game that simply belongs to the Tetris genre. Courts can struggle with such judgments, so expecting a short prompt to resolve them reliably is a tall order. Anthropic’s rule may shape what Claude will help build, but it cannot settle the broader debate over copying, transformation, and creative influence.