2017 · ソースブック（プレイを拡張するルール／オプション）
Celestial Mechanics
A rules supplement for d20-based roleplaying games that adds narrative control without changing existing character creation, combat, magic, or other rules. For actions not covered by the core system, players choose a bid die from d4 to d12 to set the potential benefits and complications, then roll a d20 with the relevant modifiers. Results of 11 or higher succeed, while 10 or lower fail. Even totals let the acting player describe the outcome; odd totals give that control to the gamemaster. Successful and failed actions are tracked with complications, reducing the gamemaster’s narrative workload.
スキルベース（スキルを購入または獲得）属性／ステータス制（STR、CON、PERなど）レベル制（XPを獲得してレベルアップ）
ゲーム情報（人数、プレイ時間、対象年齢、クレジット）の出典：BoardGameGeek。