This builds the kind of tools people actually share: name generators, personality quizzes, calculators that screenshot well. It covers the psychology of why people share (identity moments, comparison results, predictions) and the mechanics that make it work (deterministic outputs so friends get consistent results, mobile-first design for screenshots, minimal input friction). The source includes specific patterns for quiz scoring, name generation algorithms using hashed inputs, and what makes calculator results go viral (ego involvement, surprising numbers). Honest take: it's very focused on the share moment rather than sustained engagement, which is exactly right for this category. Use it when you're building something designed to spread through social sharing rather than retain users.
npx skills add https://github.com/sickn33/antigravity-awesome-skills --skill viral-generator-builder