Notes on solo RPG engines, mechanics, and principles.

Core Mechanic

All solo engines answer questions: Is there a way across the chasm? How many guards? Is the door locked?

How answers are determined is the soul of the engine:

  • Likelihood — how likely is “yes”? More likely = fewer surprise twists.
  • Narrative tension — adjusting outcomes based on story pacing and pressure.
  • Levels of success — heroic success, partial success, tragic setback.

Rules for Solo Play

  1. Rulings and enjoyment over rules
  2. Keep it simple — fewer supplements, variations, addendums
  3. Use a system you already know
  4. Scenes are the base unit — every session is a string of scenes

Engine Comparison

Mythic GME

  • Determine odds → adjust for Chaos Factor → roll Fate Question
  • Result: Exceptional Yes / Yes / No / Exceptional No
  • Random Events on doubles ≤ Chaos Factor
  • Makes for dramatic scenes with narrative momentum

MUNE

  • Determine odds (advantage/disadvantage) → roll Oracle
  • More twists and paths at a smaller, faster level
  • Lighter weight than Mythic

Location Complexity (4AU Concept)

Every ship, station, artifact, or ruin has a complexity rating. Higher = more things happening.

Rating controls how many features you roll from a table. A three-section ship probably isn’t trapped in a time loop and filled with self-replicating machines and flooded with toxic gas.

  • Every location has 1–N Big Things
  • Simple version: one table. Advanced: table of tables.
  • Games are replayable — rules for reusing maps, branching versions, re-exploring previous runs
  • Crews can leave their mark, not always for the better