The Lucky 13 Referee's Guide provides a light-weight game system that complements (and completes) the Quick Guide. Characters have Vital Statistics (attributes). Each Vital Statistic has two ratings. The first rating is placed in brackets and indicates the character's natural (starting) value, ranging from 1-10. These scores are generated from 2d6-2, re-roll zeros. Characters' second rating begins at the same level as the natural value but may change during the campaign. Vital Statistics include Strength, Fitness, Intelligence, Ability, Dexterity, Charisma, Appearance, and Destiny. Characters may have Skills but only a few samples are given--it is assumed players will generate a Skill list for Referee approval.
Actions are resolved by 2d6 plus Vital Statistic or Skill modifier compared to a Difficulty. In combat the Difficulty is the opponent's roll. Wounds are handled in an atypical way, with several minor wounds becoming a major wound, and multiple major wounds being fatal. Characters in the system cannot sustain very much damage (compared to other role-playing games). Though science-fiction in nature, the rules do support spell casting as a series of Skills.