The body is lean (~35 lines), assumes Claude's competence, and never explains concepts Claude already knows (e.g., what an ARPG or Three.js is); every line is directive guidance that earns its place.

As an instruction-only skill it carries no code, but the guidance is concrete and specific — ordered slices, named systems ('contact, damage, posture, recovery, and death'), and named validation ('unit tests, type/lint checks, production build'), so the instruction-only carve-out applies rather than a penalty.

A clear sequence (production contract → vertical slices 1–5 → runtime boundaries → validate) with explicit validation checkpoints in 'Validate before release' and named verification states (fresh start, saved continuation, loss/retry) provides feedback loops, matching the top anchor.

Under 50 lines with no external references needed and no bundle files present; the four well-organized section headers give clear navigation, so the simple-skill carve-out for progressive disclosure applies.

Lists multiple concrete actions/capabilities — 'game-loop architecture, camera and movement, zones, combat integration, content data, progression, saves, or production-ready vertical slices' — matching the top anchor for enumerating specific concrete actions.

Explicitly answers both what ('Build or extend a playable isometric action RPG in Three.js, React, or similar web technology') and when via an explicit 'Use for ...' trigger clause, satisfying the both-what-and-when anchor.

Natural terms a user would say are well covered: 'isometric action RPG', 'Three.js', 'React', 'game-loop', 'camera and movement', 'zones', 'combat', 'progression', 'saves', matching the good-coverage anchor; not merely technical jargon.

A clear niche (isometric ARPG in web tech) with distinct, domain-specific triggers makes overlap with other skills unlikely, matching the clear-niche anchor.