Build toward the shinobi fantasy, not toward encyclopedic coverage. The system is designed around four recurring experiences: techniques that grant concrete permissions, tactical discovery that changes what is possible, relationships that create pressure and leverage, and growth that alters the fiction rather than merely increasing numbers.
A new mechanic belongs only when it strengthens one of those experiences or repeatedly solves a playtest problem. A complete Naruto catalog is not a design goal. Fifteen techniques that interact coherently are more useful than four hundred copied names the GM cannot adjudicate reliably.
The core loop
The intended loop is: observe → understand → create an opening → commit → live with the consequence. Missions give that loop a larger frame; training and bonds carry consequences forward.
When extending the project, ask four questions for every mechanic:
- What rule tells the GM when and how this operates?
- Which schema owns its durable data?
- Which file holds the current state during play?
- How does the right rule/state reach context when needed?
If one answer is missing, the mechanic is documentation rather than a reliable game system.
Permission before probability
Power Tier, Technique functions, Traits, terrain, and established facts determine whether an action is possible before dice are rolled. Do not solve scale by stacking larger modifiers. If a genin cannot currently land a decisive action on an Elite opponent, the design question is what leverage can change that—not whether the roll should be 2d6−5.
Preserve player agency
Content should create situations, not scripts. NPCs need motives, limits, secrets, and pressure points. Locations need usable features. Missions need a public premise and enough hidden truth to evolve. GM instructions should never convert those ingredients into a fixed sequence of scenes.