Anthropic Nerfs Claude Again to Block Recreations of Any "Specific Existing Game"

Anthropic added a new rule to Claude Opus 5.5, flagged as "tengu_heron_brook," that blocks prompts producing "a recreation of a specific existing game, even if it is renamed or called original." The rule appeared in the changelog around October 27 and has no setting to turn it off. Claude still allows original games, games in a genre, and games built from users' own designs and assets.