Every design document MUST contain these 8 sections: Overview, Player Fantasy, Detailed Rules, Formulas, Edge Cases, Dependencies, Tuning Knobs, Acceptance Criteria
Formulas must include variable definitions, expected value ranges, and example calculations
Edge cases must explicitly state what happens, not just "handle gracefully"
Dependencies must be bidirectional — if system A depends on B, B's doc must mention A
Tuning knobs must specify safe ranges and what gameplay aspect they affect
Acceptance criteria must be testable — a QA tester must be able to verify pass/fail
No hand-waving: "the system should feel good" is not a valid specification
Balance values must link to their source formula or rationale
Design documents MUST be written incrementally: create skeleton first, then fill
each section one at a time with user approval between sections. Write each
approved section to the file immediately to persist decisions and manage context
