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Cepheus Engine vs Mothership

Compare Cepheus Engine and Mothership side by side. See differences in complexity, dice, genre, cost, and more.

Cepheus EngineMothership
GenreScifiScifi, Horror
Play StyleSandbox, Modular, Toolkit, SimulationRules-Light, Deadly, One-Shot Friendly, Survival, Atmospheric, Low-Prep, Cinematic, Fast-Paced
Core MechanicRoll 2d6 + skill level + characteristic modifier. Meet or beat 8 to succeed. Effect (margin above/below 8) determines degree of success or failure. Lifepath character creation with careers, skills, and mustering-out benefits.Roll d100 under stat/skill. Stress and panic mechanics escalate tension.
Dice2d6d100
ComplexityMediumLow
AccessibilityHighHigh
CommunityMediumMedium
LicenseOGL3rd Party License
CostFree$
PublisherSamardan PressTuesday Knight Games
Year20162022
Best ForGMs who want a fully open, hackable classic sci-fi engine for sandbox campaigns — trade, exploration, and space combat without any IP restrictions.Terrifying sci-fi horror one-shots and short campaigns. Panic table creates unforgettable moments.
HighlightsCompletely free and OGL, large third-party ecosystem, comprehensive rules covering personal combat to starship design, fully compatible with classic Traveller materialRules-light, well-regarded module library, panic system creates mechanical tension
ConsiderationsDense 200+ page SRD with no setting or adventure content, lifepath character creation can kill characters before play, assumes GM comfort with sandbox prepPanic table can cascade and end sessions abruptly, limited long-campaign support in core rules, stress mechanics can feel repetitive over extended play