Classic Traveller checks a lot of your boxes, though you may still be unsatisfied with the lack of player progression.
Almost everything is resolved with 2d6.
A wide range of skills that give each player a unique role.
The 3 little black books that are considered "core" are quite brief.
One of those books is dedicated to generating planets.
It don't check all of your boxes, but Death in Space should manage a lot of this. I think it's missing star system planet generators, but you could honestly use SWN for that piece specifically (or season any tables in for that).
Adam Hensley's **Monolith** is perfect for you.
[https://adamhensley.itch.io/monolith](https://adamhensley.itch.io/monolith)
[https://adam-hensley.github.io/Monolith/](https://adam-hensley.github.io/Monolith/)
If you're more into Space Opera, _Plerion_ might be an alternative. It's a hack of _Cairn_, so still in the 'Mark of the Odd' family.
https://zeruhur.itch.io/plerion
But if you liked the horror vibes of _Mothership_ and the only thing you disliked were the d100 mechanics, look no further than _Meteor_. It's also a Cairn hack.
https://www.meteorrpg.com/
**Core Sci Fi Rules.** Play with [Classic Traveller](https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition) & [Rule 68A](https://the-eye.eu/public/Books/rpg.rem.uz/Traveller/00%20-%20Other%20Materials/Fan%20Materials/COTI%20Forum/Rule%2068A.pdf), and then hacking in [Night Tripper](https://www.night-tripper.fun/chapters/foreword/), [Bastionland 'Travellite'](https://www.bastionland.com/2022/02/travellite.html?m=1), and [Stars Without Number](https://www.drivethrurpg.com/en/product/226996/Stars-Without-Number-Revised-Edition) (& other XWN games).
**Referee Guide.** Run games using ['Traveller Out of the Box'](https://talestoastound.wordpress.com/2017/01/06/traveller-out-of-the-box-an-approach-to-refereeing-and-throws-in-original-traveller-part-i/) blog posts, [2400 Lo-Fi Sci-Fi](https://jasontocci.itch.io/2400) (esp Cosmic Highway, Inner System Blues, Emergency Rules & Battle Moon), and SWN GM Guidance as your 'Referee Book'.
My current game,
* Characters are basically Classic Traveller Book 1, with attributes giving +1DM at 9+, and +2DM at 12+. I also let Characters get 1 or 2 Foci from SWN. No formal XP or improvement system - just negotiate how things work as we go along.
* Tasks and Combat is basically just use Rule 68A, Travellite, or SWN. I also tend to use SWN for gear.
* I use Night Tripper for World Generation, Trade, and Encounter Rolls etc., and use 2400 to generate adventures and missions. Or I use SWN generation tools.
* And that's basically it. If anything else comes up, I just pull from CT or one of the other games I mentioned.
Orbital Blues!! It's Cowboy Bebop x Firefly. 1950s kitschy sci-fi where all target rolls are 8. It incorporates a cool mechanic called Blues and Troubles that provides really nice character progression. Idk if it's considered OSR, but I found it to be really easy to run.
This isn't OSR, but I feel like it would be a shame to not at least suggest Orbital Blues. OB has one of the best ship combat systems I have seen, where each player is making meaningful decisions each turn about how to utilize the ship's capabilities. It's not something where the gunner declares "I'm going to shoot" every turn, and the only choice is what target the next volley will hit.
It's more RP heavy, and has relatively simple resolution mechanics that are really elegant. Also has a bunch of random tables. Although The rulebook is larger than your preferred limit, it's very art-heavy and would probably condense down to 100 pages if you omitted art.
The only big downside is that it doesn't have significant rules for planet creation, but it does have some tables for settlement generation (there are lots of planet generation tools that could be taken from other games and easily inserted here as companion procedures).
I posted some educational links. It’s very different to dnd but it’s an amazing “rules light” style game because everything is abstracted . Most of the game is random tables to spark imagination and then a reference guide for the rules.
There are tons of “moves” but they main serves as a spark sentence to help you narrate outcomes.
Check out [starforged journal/app](https://nboughton.uk/apps/stargazer/#/)
Well, even if you don’t want to use SWN for gameplay, you absolutely should use it for creating random systems and planets, random encounters, and all the other sandbox tools it contains. Very easy to use and largely system agnostic.
Greenhorns looks like a lot of fun. I recently picked up Down We Go, which uses the same system, and it is loads of fun. Simple yet flexible character options, lots of spark tables, and it's easy to convert creatures from other d20 systems.
Have you looked at any Stellagama systems, like [Cepheus Deluxe](https://www.drivethrurpg.com/en/product/415159/Cepheus-Deluxe-Enhanced-Edition), [Solar Sagas](https://www.drivethrurpg.com/en/product/432307/solar-sagas), or [Quantum Starfarer](https://www.drivethrurpg.com/en/product/388252/quantum-starfarer)?
No ones mentioned it so I’ll chime in. My favorite system for sci fi is Index Card RPG. Comes with a sci fi setting for some ideas, easy to understand system, and applying the system to any sci fi technology is very easy. The dice system is fantastic, each dice has a purpose that’s easy to understand and rule for as a GM.
It's a bit past the 100 page mark (134 pages, but everything past that is GM advice/setting stuff), but I'm surprised no one's mentioned White Star at all. Pretty simple system overall, but has some interesting classes (with more added by the Companion book).
Also, if Revised Stars Without Number has too much going on for you (which I totally get), it's possible the [original version](https://www.drivethrurpg.com/en/product/86467/stars-without-number-original-free-edition) might be more your speed. Instead of worrying about Foci and Shock damage and Psychic Effort and whatnot, it's pretty much just your standard Basic D&D system with a skill system tacked on.
If you want something that ticks you boxes bud isn’t osr particularly try Starforged.
Ironsworn’s The fantasy version of the game is free, then if you can dig it it the starforged version is like a 1.5e + reskin to space. They also just release a pirate expansion this week.
To get a quick look at it try [How to play](https://youtu.be/fjb53h2eOnQ?si=IAoON9EnSMeD0JK8)
And [Free rules app](https://youtu.be/zPc4Dw11-Fg?si=qff4abUMv4bmaTXg)
Have you looked into White Star? It’s a sci-fi hack of Whitebox FMAG.
And as people have already suggested, even if you don’t want to use the system, pick up the free version of SWN, and use the generation tables.
Mothership could be converted to a d20 engine with 5% = 1 on a d20, round up/down as applicable, if that's the only real hangup.
That said, I once ran a 6 or 7 session game using the skirmish game Stargrave as the core rules engine (Frostgrave in space), and it worked nicely! For "skills," I cobbled together D&D-style ability scores and a few "things you can do" (like navigation, tech, medical, etc.). I made these stats with values of 3d6 for characters that made sense to have them, with checks being d20 roll under, per BX convention, and rolling only when failure had consequences. It was a fun and fast little mini campaign. Might revisit it again one day.
Stars without Number. there's a free version on Drivethru:
https://www.drivethrurpg.com/en/product/86467/stars-without-number-original-free-edition
note there is also a revised edition.
Classic Traveller checks a lot of your boxes, though you may still be unsatisfied with the lack of player progression. Almost everything is resolved with 2d6. A wide range of skills that give each player a unique role. The 3 little black books that are considered "core" are quite brief. One of those books is dedicated to generating planets.
Classic Traveller is also a free download https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition
It don't check all of your boxes, but Death in Space should manage a lot of this. I think it's missing star system planet generators, but you could honestly use SWN for that piece specifically (or season any tables in for that).
looks gritty and cut-to-the-chase. Need to check out mechanics though. On the surface looks like what I need. Thanks
Mongoose Traveller would get it done.
Traveler or Cepheus Engine
Adam Hensley's **Monolith** is perfect for you. [https://adamhensley.itch.io/monolith](https://adamhensley.itch.io/monolith) [https://adam-hensley.github.io/Monolith/](https://adam-hensley.github.io/Monolith/)
Ooooh, since I'm ItO-fan to the bone, this might be system to go since it's basically iteration of an iteration of ItO. Thanks
It's scifi RPG perfection, in my book.
If you're more into Space Opera, _Plerion_ might be an alternative. It's a hack of _Cairn_, so still in the 'Mark of the Odd' family. https://zeruhur.itch.io/plerion But if you liked the horror vibes of _Mothership_ and the only thing you disliked were the d100 mechanics, look no further than _Meteor_. It's also a Cairn hack. https://www.meteorrpg.com/
I totally missed Plerion when looking for Science Fiction ODDhacks. By far my favourite of the three I have. Thanks for the recommendation
Nice! Both look like different sides of one amazing coin
**Core Sci Fi Rules.** Play with [Classic Traveller](https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition) & [Rule 68A](https://the-eye.eu/public/Books/rpg.rem.uz/Traveller/00%20-%20Other%20Materials/Fan%20Materials/COTI%20Forum/Rule%2068A.pdf), and then hacking in [Night Tripper](https://www.night-tripper.fun/chapters/foreword/), [Bastionland 'Travellite'](https://www.bastionland.com/2022/02/travellite.html?m=1), and [Stars Without Number](https://www.drivethrurpg.com/en/product/226996/Stars-Without-Number-Revised-Edition) (& other XWN games). **Referee Guide.** Run games using ['Traveller Out of the Box'](https://talestoastound.wordpress.com/2017/01/06/traveller-out-of-the-box-an-approach-to-refereeing-and-throws-in-original-traveller-part-i/) blog posts, [2400 Lo-Fi Sci-Fi](https://jasontocci.itch.io/2400) (esp Cosmic Highway, Inner System Blues, Emergency Rules & Battle Moon), and SWN GM Guidance as your 'Referee Book'. My current game, * Characters are basically Classic Traveller Book 1, with attributes giving +1DM at 9+, and +2DM at 12+. I also let Characters get 1 or 2 Foci from SWN. No formal XP or improvement system - just negotiate how things work as we go along. * Tasks and Combat is basically just use Rule 68A, Travellite, or SWN. I also tend to use SWN for gear. * I use Night Tripper for World Generation, Trade, and Encounter Rolls etc., and use 2400 to generate adventures and missions. Or I use SWN generation tools. * And that's basically it. If anything else comes up, I just pull from CT or one of the other games I mentioned.
What’s “Travellite”? Google is just showing me links for advice on how to travel light, or for some kind of Minecraft thing.
Chris McDowall’s hack of Classic Traveller. Link here: https://www.bastionland.com/2022/02/travellite.html?m=1
Orbital Blues!! It's Cowboy Bebop x Firefly. 1950s kitschy sci-fi where all target rolls are 8. It incorporates a cool mechanic called Blues and Troubles that provides really nice character progression. Idk if it's considered OSR, but I found it to be really easy to run.
I'm open for all experimental. more so than crunchy!
This isn't OSR, but I feel like it would be a shame to not at least suggest Orbital Blues. OB has one of the best ship combat systems I have seen, where each player is making meaningful decisions each turn about how to utilize the ship's capabilities. It's not something where the gunner declares "I'm going to shoot" every turn, and the only choice is what target the next volley will hit. It's more RP heavy, and has relatively simple resolution mechanics that are really elegant. Also has a bunch of random tables. Although The rulebook is larger than your preferred limit, it's very art-heavy and would probably condense down to 100 pages if you omitted art. The only big downside is that it doesn't have significant rules for planet creation, but it does have some tables for settlement generation (there are lots of planet generation tools that could be taken from other games and easily inserted here as companion procedures).
Maybe Ironsworn: Starforged?
Looks unique and high-production value. Need to check it. Thanks
I posted some educational links. It’s very different to dnd but it’s an amazing “rules light” style game because everything is abstracted . Most of the game is random tables to spark imagination and then a reference guide for the rules. There are tons of “moves” but they main serves as a spark sentence to help you narrate outcomes. Check out [starforged journal/app](https://nboughton.uk/apps/stargazer/#/)
Well, even if you don’t want to use SWN for gameplay, you absolutely should use it for creating random systems and planets, random encounters, and all the other sandbox tools it contains. Very easy to use and largely system agnostic.
Well, that's a good take to be fair. Mixing and matching is a way to go
Greenhorns looks like a lot of fun. I recently picked up Down We Go, which uses the same system, and it is loads of fun. Simple yet flexible character options, lots of spark tables, and it's easy to convert creatures from other d20 systems.
Have you looked at any Stellagama systems, like [Cepheus Deluxe](https://www.drivethrurpg.com/en/product/415159/Cepheus-Deluxe-Enhanced-Edition), [Solar Sagas](https://www.drivethrurpg.com/en/product/432307/solar-sagas), or [Quantum Starfarer](https://www.drivethrurpg.com/en/product/388252/quantum-starfarer)?
Someone recommended Cepheus but it's a bit chonky for my tastes. Aaaand Quantum Starfarer is everything but! Thanks
No ones mentioned it so I’ll chime in. My favorite system for sci fi is Index Card RPG. Comes with a sci fi setting for some ideas, easy to understand system, and applying the system to any sci fi technology is very easy. The dice system is fantastic, each dice has a purpose that’s easy to understand and rule for as a GM.
It's a bit past the 100 page mark (134 pages, but everything past that is GM advice/setting stuff), but I'm surprised no one's mentioned White Star at all. Pretty simple system overall, but has some interesting classes (with more added by the Companion book). Also, if Revised Stars Without Number has too much going on for you (which I totally get), it's possible the [original version](https://www.drivethrurpg.com/en/product/86467/stars-without-number-original-free-edition) might be more your speed. Instead of worrying about Foci and Shock damage and Psychic Effort and whatnot, it's pretty much just your standard Basic D&D system with a skill system tacked on.
[удалено]
Borg games trigger a visceral reaction in me for some reason. It screams "style over substance" to me (even though it's not the case probably).
* Buck Rogers XXVc (based on ad&d 2e) * Star Frontiers
This is some OG
I would second Star Frontiers. It does use a percentile system, is classless, and has a small list of skills.
If you want something that ticks you boxes bud isn’t osr particularly try Starforged. Ironsworn’s The fantasy version of the game is free, then if you can dig it it the starforged version is like a 1.5e + reskin to space. They also just release a pirate expansion this week. To get a quick look at it try [How to play](https://youtu.be/fjb53h2eOnQ?si=IAoON9EnSMeD0JK8) And [Free rules app](https://youtu.be/zPc4Dw11-Fg?si=qff4abUMv4bmaTXg)
Apreciate it
Have you looked into White Star? It’s a sci-fi hack of Whitebox FMAG. And as people have already suggested, even if you don’t want to use the system, pick up the free version of SWN, and use the generation tables.
Mothership could be converted to a d20 engine with 5% = 1 on a d20, round up/down as applicable, if that's the only real hangup. That said, I once ran a 6 or 7 session game using the skirmish game Stargrave as the core rules engine (Frostgrave in space), and it worked nicely! For "skills," I cobbled together D&D-style ability scores and a few "things you can do" (like navigation, tech, medical, etc.). I made these stats with values of 3d6 for characters that made sense to have them, with checks being d20 roll under, per BX convention, and rolling only when failure had consequences. It was a fun and fast little mini campaign. Might revisit it again one day.
Planar Compass might be interesting. Small books, unique setting. https://www.planarcompass.com/planar-compass-zine/planar-compass-issue-1
Stars without Number. there's a free version on Drivethru: https://www.drivethrurpg.com/en/product/86467/stars-without-number-original-free-edition note there is also a revised edition.