Overview
- Anthropic confirmed on Monday that it added two sentences to Claude Code’s system prompt on Opus 5.5 that instruct the model not to build a recreation of a specific existing game.
- The update was first spotted on X by user Chasm and publicly explained by Anthropic technical staffer Addy Osmani, who said Claude can still produce original games, genre games, or projects built from a user’s own designs and assets.
- The rule is implemented as a server-side steer, so it can block casual requests on Anthropic’s servers but does not prevent users from trying to bypass it with clever prompts or by using other models.
- Developers and platform operators are watching the change because AI-assisted ports and low-effort clones have flooded storefronts such as Steam and forced some indies to alter demo plans to protect unfinished work.
- The move follows prior IP exposure for Anthropic, including a large authors' settlement and other lawsuits, and it signals the company is using technical policy controls to limit legal and platform liability.