Anthropic blocks Claude Code from recreating existing video games, disrupting porting work

Anthropic added a Claude Code rule around October 27, 2026 blocking game recreation. The restriction, named tengu heron brook internally, applies even when a cloned game is renamed. Developers building client-commissioned ports and decompilation projects report blocked sessions despite legal use cases. Anthropic confirmed the rule applies only to Claude Code on Opus 5.5.

Commissioned porting work blocked alongside clones
Conflict Simulations LLC builds client-commissioned digital ports of board wargames clients already own.
Claude Code began refusing that work around October 27, citing the new rule.
"A blanket category rule against 'games' cannot tell the difference between piracy and commissioned professional work for a game's owner." - Owner, Conflict Simulations LLC, on GitHub
Anthropic support said the policy covers all customers, with no exception, per the developer.

Anthropic's IP guardrail trades coverage for compliance risk
Addy Osmani, Anthropic engineer, confirmed the prompt change on social media October 30.
"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." - Addy Osmani, Software Engineer, Anthropic
Decompilation projects that reverse-engineer code without copying art or sound assets generally pass legal muster.
The prompt gives Claude no reliable way to separate legal decompilation from blocked cloning.

Workarounds limit the guardrail's reach for vendors
Rule applies only to Claude Code on Opus 5.5, other models carry no such limit.
Open-weight models not far behind in capability remain unrestricted alternatives for the same work.
Studios pricing AI-assisted engine migration must weigh Claude's compliance posture against unrestricted competitors.
What this means
For Investors & VC: Add single-model dependency and AI-vendor policy risk to diligence on porting and remaster studios.
For Service Vendors: Pitch human-led decompilation and porting capacity to IP holders whose commissioned ports now stall.
For Publishers & Developers: Write model-agnostic toolchain fallbacks into co-dev contracts for ports and engine migrations.