Science‑Fiction & Science‑Fantasy RPG Mega‑Guide
Playability, umpire (GM) ease, add‑ons, cost bands, and “how fast can we start?” — from Traveller to Stars Without Number, narrative to crunchy.
Brassy TL;DR Picks
Fastest Start Stars Without Number (Free) — sandbox tools, OSR-simple.
Classic Core Traveller / Cepheus — iconic, mid‑crunch, expandable.
Narrative / Low‑Prep Scum & Villainy — crews, flashbacks, score‑based play.
Transhuman Eclipse Phase — idea‑rich, heavier but rewarding.
Sci‑Fantasy Starfinder — d20 comfort, big toolbox (big books).
Horror One‑Shot Mothership — tense, quick to table.
Classic Core Traveller / Cepheus — iconic, mid‑crunch, expandable.
Narrative / Low‑Prep Scum & Villainy — crews, flashbacks, score‑based play.
Transhuman Eclipse Phase — idea‑rich, heavier but rewarding.
Sci‑Fantasy Starfinder — d20 comfort, big toolbox (big books).
Horror One‑Shot Mothership — tense, quick to table.
Choose in 3 Minutes
- Play tonight: SWN (free) with its sector/mission generators, or Mothership for sci‑horror.
- Team knows d20: Starfinder (sci‑fantasy) or 5E‑adjacent sci‑fi (e.g., Esper Genesis).
- Like ships/trade/sim: Traveller / Cepheus — add trading & patrons as needed.
- Low GM prep: Scum & Villainy — scores, clocks, downtime handle structure.
- Near‑future politics: The Expanse (AGE) or Eclipse Phase for deeper themes.
- Mechs: Lancer — crunchy tactical fights, slick vibe.
Traveller (all editions) & Cepheus Engine
Vibe: Classic hard‑ish space operaCrunch: MediumGM Prep: MediumRead to Start: ~20–30 ppCost: £0–£30+ (edition)
Why run it: The free‑trader fantasy: careers, patrons, ships, trade. Cepheus offers open‑content flexibility and tons of third‑party support.
Start here: Task system, character creation, simple ship ops, one subsector — that’s session 1.
Add‑ons: Sector tools, ship design, trade, mercenary tickets. Umpiring is steady once you pick your sub‑systems.
Watch‑outs: Many editions; settle on one to avoid drift.
MGS link: Traveller hub
Stars Without Number (Free & Revised)
Vibe: OSR sandboxCrunch: Low–MedGM Prep: LowRead to Start: ~15–20 ppCost: Free / Low
Why run it: Best‑in‑class GM tools: sectors, factions, missions, encounters. Improv‑friendly and lethal enough to matter.
Sibling: Worlds Without Number for fantasy; lots of cross‑usable tools.
MGS link: SWN hub
Starfinder (Science‑Fantasy, d20)
Vibe: Bright, maximal, magic+scienceCrunch: HighGM Prep: Med–HighRead to Start: Core + pregensCost: Mid–High
Why run it: Easy on‑ramp for d20 players; oceans of content. Use Beginner material to dodge bloat early.
Scum & Villainy (Forged in the Dark)
Vibe: Crew heists & jobsCrunch: LowGM Prep: LowRead to Start: ~12–18 ppCost: Low–Mid
Why run it: Scores, position/effect, flashbacks; GM focuses on drama while the system carries pacing.
Mothership (Sci‑Fi Horror)
Vibe: Alien‑style dreadCrunch: LowGM Prep: Low–MedRead to Start: ~10–15 ppCost: Low
Why run it: Panic/stress rules drive tension; perfect for one‑shots or short arcs.
ALIEN RPG (Year Zero Engine)
Vibe: Licensed survival horrorCrunch: Low–MedGM Prep: MedRead to Start: ~20 pp + scenarioCost: Mid
Why run it: Cinematic mode is ultra‑accessible; panic dice escalate beautifully.
Eclipse Phase (Transhuman)
Vibe: Mind uploads & shellsCrunch: Med–HighGM Prep: MedRead to Start: ~30–40 ppCost: Mid (SRD options)
Why run it: Idea‑dense setting for groups who like philosophy and politics with their action.
Lancer (Tactical Mecha)
Vibe: Stylish mechsCrunch: High (combat)GM Prep: MedRead to Start: ~25–35 ppCost: Mid
Why run it: Deep, satisfying tactical layer; narrative between missions stays flexible.
The Expanse (AGE System)
Vibe: Near‑future realismCrunch: MediumGM Prep: MediumRead to Start: ~20–30 ppCost: Mid
Why run it: Credible tech & politics; a balanced midpoint between sim and story.
Star Wars (Edge/Age/Force — Narrative Dice)
Vibe: Cinematic pulpCrunch: MediumGM Prep: Low–MedRead to Start: ~20 ppCost: Mid
Why run it: Advantage/Threat results fuel big‑screen storytelling with minimal prep.
MGS link: Edge of the Empire notes
D6 Space (Generic Space Opera)
Vibe: Classic dice‑pool funCrunch: Low–MedGM Prep: MediumRead to Start: ~15 ppCost: Often Low
Why run it: Straightforward, hackable backbone for custom settings.
GURPS Space / Transhuman Space
Vibe: Realism toolkitsCrunch: Med–High (modular)GM Prep: MediumRead to Start: pick modulesCost: Mid
Why run it: Build precisely the campaign you want; Transhuman Space for near‑future hard‑SF.
Savage Worlds (Sci‑Fi Companion)
Vibe: Pulpy & fastCrunch: Medium (swingy)GM Prep: Low–MedRead to Start: ~12–20 ppCost: Low–Mid
Why run it: Fast action, vehicles, starfaring — great for set‑piece nights.
Science‑Fantasy & Multi‑Genre
Starfinder
d20 bones with spells and super‑science. Start with beginner material to avoid overload.
RIFTS (Palladium)
Maximalist cross‑genre chaos — mechs, magic, post‑apoc. Crunchy; thrives with an experienced umpire.
Numenera (Cypher)
Far‑future wonder; rules are streamlined and discovery‑driven.
Costs & Page Counts — Practical Bands
- Cost bands: Free (£0), Low (£1–£10), Mid (£11–£30), High (£31+). Many lines have SRDs/quickstarts.
- Start‑Tonight Plan: Quickstart + pregens; simple mission (heist/salvage/SOS); 1–2 meaningful combats.
- GM sanity: Pick 2–3 subsystems for Session 1; “unlock” more later.
90‑Minute Starter Recipe (Any System)
- Pitch (2 min): “Small crew, big debt; derelict sends a weak SOS.”
- PCs (10–15): Pregens/fast builds + one hook each.
- Scene 1: Dock & breach (skill + single hazard).
- Scene 2: Complication (trap/hostile/timer) + moral choice.
- Scene 3: Extraction (chase/combat/negotiation clock).
- Epilogue: Payout, new problem, next hook.
Related MGS Hubs
Costs and “pages to play” are ballpark for quick choosing. Check current SRDs/quickstarts for exact details. Want printable one‑page cheat sheets per system? Say the word and I’ll convert these cards.
Always difficult to choose which system from a choice of outstanding rules....
...from the highly-rated but pre-determined & relatively expensive Star Wars franchise through to the excellent Stars Without Number there are some great rules, many add-ons.
Many who have played Traveller, the first successful Sci-fi RPG, will have had many characters die in what is an often deadly, but fun, character generation process.... but it still has massive support with the ever popular Spinward Marches fully mapped....
.... and we should not forget to mention the excellent Eclipse Phase and Diaspora.
May the Force be with you.... or dare I say Live Long & Prosper?
...from the highly-rated but pre-determined & relatively expensive Star Wars franchise through to the excellent Stars Without Number there are some great rules, many add-ons.
Many who have played Traveller, the first successful Sci-fi RPG, will have had many characters die in what is an often deadly, but fun, character generation process.... but it still has massive support with the ever popular Spinward Marches fully mapped....
.... and we should not forget to mention the excellent Eclipse Phase and Diaspora.
May the Force be with you.... or dare I say Live Long & Prosper?
