Stars Without Number uses a mix of 2d6 skill checks and d20 combat rolls, combining OSR-style danger with modern skill-based gameplay.

The Core Roll: 2d6 + Skill + Attribute

Most non-combat actions use 2d6 + skill level + relevant attribute modifier.

  • Roll 8+ for typical difficulty
  • Roll 10+ for challenging tasks
  • Roll 12+ for very difficult tasks

Example: Hacking a security terminal

  • Roll 2d6 + Program skill (level 1) + Intelligence modifier (+1) = 2d6+2
  • Need 10+ to succeed

Attributes

Six core attributes, each with a modifier:

  • Strength (STR): Physical power and melee combat
  • Dexterity (DEX): Agility, reflexes, and ranged combat
  • Constitution (CON): Health and endurance
  • Intelligence (INT): Logic, technical skills, and knowledge
  • Wisdom (WIS): Perception, intuition, and mental fortitude
  • Charisma (CHA): Social influence and leadership

Attribute Modifiers:

  • 3: -2 modifier
  • 4-7: -1 modifier
  • 8-13: +0 modifier
  • 14-17: +1 modifier
  • 18: +2 modifier

Skills

Skills range from level 0 (trained) to level 4 (mastery).

  • Level 0: Basic training, no penalty
  • Level 1-4: Increasing expertise (+1 to +4)
  • Untrained: -1 penalty to the roll

Common Skills

  • Combat: Punch, Shoot, Stab
  • Technical: Fix, Program, Pilot
  • Social: Connect, Lead, Trade
  • Knowledge: Know, Notice, Sneak

Combat

Combat uses d20 + bonuses vs. Armor Class (AC).

Attack Roll

Roll d20 + Attack Bonus + Skill Level + Attribute Modifier

  • Warriors add their level to attack rolls
  • Hit if the total meets or exceeds the target’s AC

Damage

Roll weapon damage (e.g., 1d8 for a laser pistol) on a hit.

Initiative

Roll 1d8 + DEX modifier at the start of combat.

Saving Throws

When facing danger, roll a d20 against your save target:

  • Physical: Resist toxins, disease, physical effects
  • Evasion: Dodge explosions, traps, area attacks
  • Mental: Resist psychic powers, fear, mind control

Roll equal to or higher than your save value to succeed.

Hit Points

HP represents luck, stamina, and minor wounds. At 0 HP, you’re mortally wounded and need immediate medical attention.

  • Most characters start with 1d6 + CON modifier HP
  • Warriors and other classes may have more
  • Combat is deadly—retreat when necessary

Experience & Advancement

Gain XP through:

  • Completing missions
  • Overcoming challenges
  • Exploring new locations
  • Achieving character goals

Advancement occurs at specific XP thresholds, typically gaining:

  • More HP
  • Better skills
  • New class abilities
  • Improved saves

“Roll high, survive longer.”