Anthropic blocks Claude Code from rebuilding existing video games

What you could do with it

• A developer could vibe-code an original game from scratch using only their own designs and assets with Claude Code ¹.
• A game enthusiast could switch to a different AI model or service to continue porting console games to PC ¹.
• A hobbyist could run open-weight models or operate completely offline to decompile and recompile existing games without relying on Claude Code ¹.

What changed

On October 27, 2026, people who follow game decompilation noticed that Claude Code started picking up a new hidden rule behind a setting called "tengu_heron_brook" ¹. The rule tells the model to build original games using only users' own designs and assets, instead of taking content from games already on the market .

A few days later, Anthropic programmer Addy Osmani confirmed that the company was adding two new sentences to Claude Code's Claude Opus 5.5 model ¹. He said that recreating someone else's intellectual property goes against Claude's usage policy, and that users should only be able to "vibe-code" — a style of casual, prompt-driven programming — original games . Osmani also said Anthropic would keep tweaking the new rules to find "the right balance" .

The bigger trend

AI-assisted decompilation and recompilation — the process of taking old game code apart and rebuilding it — has taken off fast. Developers and hobbyists have been using it to "port," or convert, console-exclusive games to PC and vice versa ¹. Projects such as AnyPS5 are even trying to turn PlayStation 5 games into "native" PC titles using AI help .

This wave of AI coding has disrupted human-led research efforts too. The decomp.dev website, which tracked and documented how old game code worked, has shut down because AI-assisted coding made its detailed research feel less necessary ¹. Instead of painstakingly reverse-engineering code line by line, many people now fork existing decompilation projects and let AI finish the job, or race to port games to different platforms first .

What happens next

Claude Code may no longer be the go-to tool for game recreations, but the broader trend is unlikely to stop. People looking to decompile or recomp existing games have several alternatives: they can move to different AI models and services, take advantage of open-weight models that are advancing quickly, or operate completely offline ¹. The ability to turn one game platform into another with AI help is not going away — it is just moving elsewhere .

This story reports on a trend for information only. It is not advice or encouragement to do any of it.

Key facts

• Anthropic updated Claude Code on October 27, 2026 to block prompts asking it to recreate existing video games
• The change affects the Claude Opus 5.5 model and applies to anyone using vibe-coding to build games
• The decomp.dev research website has shut down because AI-assisted coding undermined its detailed manual work
• Other AI models and open-weight options remain available for people who still want to decompile games

Sources

1. Anthropic tells Claude Code to stop recreating existing video games — techspot.com