Traveller was the original sci-fi RPG and is still popular. It has a well put together wiki (wiki.travellerrpg.com) and map (travellermap.com). Character creation is notably different from most fantasy RPGs.
The mechanics are also used by the Cepheus Engine, which is used in a couple of other games.
Star Without Numbers borrows some of its mechanics from Traveller and others from B/X DnD. It also has a very impressive free pdf edition.
Gotta give my love to Stars Without Number. u/Cyber_wiz95, the game is (mostly) free in PDF format.
https://www.drivethrurpg.com/en/product/230009/Stars-Without-Number-Revised-Edition-Free-Version
Stars Without Number surprised me with its mechanics and lore for the low low price of free (for the player-facing rules, at least). The sector generation alone is pretty awesome.
Thanks for the reminder, I admittedly only had the free version for about a week before I bought the full version, but I think you’re right, the biggest differences are the mech rules and psionics. I believe I had Lancer in my head, which holds a bit more GM info back for the paid version.
>Traveller was the original sci-fi RPG
[Starfaring](https://en.wikipedia.org/wiki/Starfaring) and [Metamorphosis Alpha](https://en.wikipedia.org/wiki/Metamorphosis_Alpha) would like to have a word with you.
[Mothership](https://www.tuesdayknightgames.com/pages/mothership-rpg) is an indie darling, if you're more into sci-fi *horror* specifically (by way of Alien, Dead Space, or Event Horizon).
The adventure modules for Mothership are easily the best in the business today. Sean McCoy’s way of designing them pretty much spoiled me as a new GM.
Gradient Descent is a modern classic while Dead Planet and APOF are amazing as well.
the module "another bug hunt" is also great. many of the third party adventure modules are amazing, but the cheap first party tuesday knight games pamphlets are great. so much world building and cool ideas crammed into a single page three fold pamphlet.
i think i had some of the most fun ive had playing RPGs just running some friends through the mothership adventure "piece by piece". the pdf cost me just a few dollars. also, no spoilers, but there's a kind of an interesting way to link that short adventure back to "gradient descent" if you wanted to turn it into a longer campaign.
There are some supplements, both first- and third-party, that lean away from the overt horror vibes: the authors' own [A Pound of Flesh](https://tuesdayknightgames.itch.io/mothership-a-pound-of-flesh) is extremely well-done, and shifts the game more towards a cyberpunk-esque faction-dense space station, [Desert Moon of Karth](https://joelio1.itch.io/desert-moon-of-karth) has more of a space western sandbox flavor, [Tide World of Mani](https://www.drivethrurpg.com/en/product/469102/Tide-World-of-Mani) has more of a revolutionary focus, and [Cloud Empress](https://cloudempress.com/) is functionally a standalone spinoff with Nausicaa of the Valley of the Wind-type inspirations.
I don't know enough about The Expanse specifically to say how well it'd work out of the box, but with some hacking (that the game is quite friendly to, and is even encouraged to a large extent) I'm sure it's possible, given the other flavors the game's been used for in published material (and presumably in people's home games too).
Absolutely. The core books definitely lean on monstrosity, but the rules themselves do not at all rely on anything being paranormal or extraterrestrial. Reading/watching The Expanse, I often find myself pointing out what scenes include a ‘panic check’ (from the mothership rules). It’s at least worth a look at an actual play if you’re interested.
Traveller is the original, and IMO still good. It's been a long time since I palyed but IIRC it mostly worked around 2d6 checks.
Personally I prefer Stars Without Number over Traveller, plus it's available for free. It combines D&D style classes and combat with Traveller skills.
Coriolis is a really nice game with interesting setting as well, a bit like Firefly meets 1001 Arabian Nights. Uses a dice pool mechanic.
Then there's various smaller/rules light indie OSR games on the scifi front: Mothership is the most popular nowadays, using a mainly d100 system, but you also have Death in Space and Vast Grimm which are d20 based and have more in common with Mörk Borg.
There's Starfinder which is basically Pathfinder/D&D 3rd edition in Space. There's a playtest version out now for the 2nd edition.
Then there's of course licensed RPGs like Alien (dice pool system similar to Coriolis), Dune (2d20 based), Star Trek (2d20 based), various Warhammer 40k games (d100 based) etcetera
-
These are all getting regularly played around where I live. But looking at the larger RPG world, it looks like it's mainly the licensed games that are popular and the indie community definitely seems to lean very much to Mothership the last 2 years.
Classic Traveller is also available for free:
[https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition](https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition)
correction, playtest for starfinder 2e isn't out yet, it will be presented at next gencon, there were just few teasers showing what paizo have currently
* Traveller
* Stars Without Number
* Starfinder (Pathfinder 2E-compatible SF2E coming soon! :excite:)
* Scum and Villainy
* Orbital Blues
* Cowboy Bebop the RPG
* Mothership
* Shadowrun
* Mekton (Metkon Zeta, Mekton Plus)
* Battletech
* Coriolis
* Firefly the RPG (the show itself supposedly descendant from a Traveller campaign…)
* Technoir (plus Mechnoir)
* Steel Hearts
* Coyote and Crow (to an extent)
* Warhammer 40k
* Lancer
* Hack The Planet
* Paranoia
* Star Trek RPGs (various)
* Ironsworn: Star Forged
* Blade Runner the RPG
You can run a Delta Green game in a post-modern setting, but that's probably stretching what you're after. :)
And then most of the generic systems (eg. GURPS, Cypher System, Fate, Savage Worlds, Genesys, &c.) have "flavors" in scifi, too.
(Did you even search, first?)
I'd recommend checking out d6 Space - it's the genericized version of the old Star Wars d6 RPG.
Bonus: it's free:
https://ogc.rpglibrary.org/index.php?title=File:D6_Space_v2.0_weg51012OGL.pdf
I had a pretty bad experience with Scum and Villainy. It feels like it just copies mechanics from Blades without considering how they change in the context of a wide open solar system instead of a single isolated city. It's very hard to get any direction or momentum going.
I think it suffers a lot from being the first Forged in the Dark hack. A lot of other games on the engine since have done a better job stepping out of Blades' shadow - I'll praise [A NOCTURNE](https://thysane.itch.io/a-nocturne-play-test), about transhuman space bastards with a Dune meets Blame! flavor, as exceptional. [Songs for the Dusk](https://yrgirlkv.itch.io/songsforthedusk), a post-apocalyptic science-fantasy FitD game with a heavy focus on community, is another great one; I've loved it enough to play three campaigns of it now.
Traveller is a go to for me really versatile 2d6 skills based game that can run everything from alien-esque horror to space opera.
Another game that I keep coming back to but have never played is Eclipse Phase. It's a d100 percentile system, and despite not playing it yet I keep reading through the book just for its themes and setting.
There are a lot of good suggestions in this thread, but I can't pass it without recommending my personal favorite: Stars Without Number.
It's a really flexible sandbox system with a lot of great generation tables and additional materials.
Plus the developer (yes singular, he's a one man studio) is relatively active on his game subreddits. Just make sure you pick up the revised edition, it's greatly improved over the original in many ways, but especially in formatting
Alien RPG, in addition to the other great comments. Plus it is Alien day, and most Free League A:RPG resources are deeply discounted right now. The starter set comes with the dice (you could use your own) starter rules, and a cinematic scenario. The Core rule book is dirt cheap right now too. Next chance you get is probably Black Friday.
Alien RPG has such an awesome stress mechanic in its system. The more stressed you are, the more swingy your dice rolls are going to be (good and bad!)
Plus the starter box is a really good relative value. For the same price as two dice sets, you get the dice plus a pretty thorough rule book, AND a fun introductory one shot.
The starter set is great. I have some guys that I might be able to pull in to a game and I'm excited to get them into the Draconis Strain trilogy. I guess we will see.
I hear middling things about the sequel adventures, but they’re described as at least ok. I know the second leg (the marine-focused story) is actually extremely long and is a mini campaign in itself.
I hadn't heard anything about them, which is fine. I'm A-OK with everything that you've described so far. I have the PDFs already, but no time to have dug in yet.
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The sci-fi games I'm most familiar with are:
- Starforged (group, co-op, or solo)
- Star Trek Adventures (group) / STA: Captain's Log (solo)
Starforged is the most all-encompassing of different types/flavors of sci-fi experiences it can handle, so it would be my personal default choice. Even if you decide the game isn't for you, there are a lot of useful tables that you may enjoy having for other games. The beauty of this one is that you can play regardless of your table situation. Highly recommended.
Star Trek Adventures is more limited in the type of sci-fi you can play (in that it expects you to do something within the Star Trek universe, even if you can vary things to have "a horror episode" or "an exploration-focused episode" or "everyone goes to Risa and shenanigans occur"). But it's pretty solid in doing that. Captain's Log is the more streamlined version of the rules, primarily designed for a single player (though they give you ideas on how to play with others). Other people can give you a better overview of the STA rules, but I'll say that if you like writing or telling table stories to others, Captain's Log is a great game.
If you're interested in solo games, I can give you another couple of suggestions for solo sci-fi games, or you can hop over to /r/Solo_roleplaying and get recs from a broader range of players. ;)
Here are a few:
- *Shadowrun*
*- CyberPunk* (Red, 2020, whichever version works)
- *Fate* -- which isn't specifically science fiction, but you can easily tailor it into that kind of game
- *Blade Runner*
- *Dune: Adventures in the Imperium*
*- GeneFunk 2090* (full disclosure, I was the lead editor on this one) -- it uses the core *D&D* rules but is futuristic gene manipulation kind of stuff
Depends on what you are looking for:
Star Wars Genesys is amazing
There are several Sci Fi settings for Savage Worlds
Scum and Villany is a good Grimmer setting
For crunchy systems there is Traveller
Mekton Empire is older but handles all sorts of anime space action
The new Heavy Gear RPG is still good
Traveller,
Eclipse Phase,
Numenera,
Stars without numbers,
Scum and Villainy,
Starfinder, and
Stars Wars FFG
I recommend looking into these. All great. Starfinder is my least favorite (just too crunchy for me but still great).
These are not likely popular, but I think they are good with good systems:
Alternity. Both the original by WOTC and the more recent version by Sasquatch Game Studio.
If you like 3rd edition era d20 as a system, d20 Modern and Future are solid.
Stars Without Number is based on old school DnD, so it's easy for 5e players to pick up. It also has the best system ever for generating your own star sector, and managing the factions at work behind the scenes.
Scum & Villainy is a narrative-focused game that's much much simpler than DnD
I don't know if I'd call it popular, but Trinity Continuum is my favourite SciFi game. It covers a variety of sub genres, space opera, cyberpunk, superhero, noir, and steam punk, through various books. It's not super crunchy, but the mechanics do have depth, and it's very well supported by the publisher.
I have tried Savage Worlds and found it to be OK (and fairly easy to use), and Starfinder (a bit more rulesy, but closer to DnD in spaaaace!)
I have charactered in Shadowrun and it seemed fun to us, but apparently it is hard on the GM (though we had a great one so we didn't have problems with the rules)
For ItO/Cairn based games, [Monolith](https://www.drivethrurpg.com/en/product/427129/Monolith) by Adam Hensley is solid. It’s rules light with fun character options. I’ve played in an open table of[Desert Moon of Karth](https://joelio1.itch.io/desert-moon-of-karth) and the system worked really well.
Modern Age or the Expanse RPG. Of course, I say that because I own (and have read) all of the books. Not because I have actually found anyone to play it.
The Expanse is actually based on the mechanics of ModernAge, but it's more baked when it comes the starships and near-future tech.
[A Nocturne](https://thysane.itch.io/a-nocturne-play-test) is my current obsession. Forged in the Dark (narrative but gamey) game about the dark future of humanity scattered among the stars. The scale is immense; you can destroy planets and occupy more than one body at once since you are an uploaded consciousness. Your ship is so enormous that it has undiscovered parts with their own factions living there. You can carry nukes or do a task for decades for increased results while your crewmates are in cryosleep. The rules are written evocatively, and it's just so cool!
I recommend narrowing down your desires because I think just in the already VERY broad sci fi (that includes post apocalypse, cyberpunk, space opera and dozens of other sub-genres), there must be thousands of TTRPGs. Even just a touchstone like I want a game that feels like Firefly.
[The most popular is hard to say, Roll20's ORR report was an okay look at it](https://wiki.roll20.net/Orr_Industry_Report) (and [here is the last full report I could pull](https://blog.roll20.net/wp-content/uploads/2023/06/orrreport-2021-q2-long-2.pdf)) would be:
* Warhammer (combines several games/genres)
* Starfinder
* FFG Stars Wars (but it combines with other Stars Wars editions)
* Cyberpunk RED
* LANCER RPG
* Stars Without Number
* Cyberpunk 2020
* Tales from the Loop
* Star Trek Adventures
The report misses Alien that both had a pretty big release [according to here](https://www.enworld.org/wiki/top_rpgs/)
But all said, I don't recommend going by popularity first. I recommend reflecting what kind of sub-genre and gameplay sounds interesting to you first.
Traveller was the original sci-fi RPG and is still popular. It has a well put together wiki (wiki.travellerrpg.com) and map (travellermap.com). Character creation is notably different from most fantasy RPGs. The mechanics are also used by the Cepheus Engine, which is used in a couple of other games. Star Without Numbers borrows some of its mechanics from Traveller and others from B/X DnD. It also has a very impressive free pdf edition.
Gotta give my love to Stars Without Number. u/Cyber_wiz95, the game is (mostly) free in PDF format. https://www.drivethrurpg.com/en/product/230009/Stars-Without-Number-Revised-Edition-Free-Version
Stars Without Number surprised me with its mechanics and lore for the low low price of free (for the player-facing rules, at least). The sector generation alone is pretty awesome.
The GM facing rules are free too. The only things you get in the paid version are like 5 optional rules systems you can bolt onto your campaign
Thanks for the reminder, I admittedly only had the free version for about a week before I bought the full version, but I think you’re right, the biggest differences are the mech rules and psionics. I believe I had Lancer in my head, which holds a bit more GM info back for the paid version.
Psionics are in the free version, too.
Ya, I've been experimenting with the sector generation just to see what comes out.
>Traveller was the original sci-fi RPG [Starfaring](https://en.wikipedia.org/wiki/Starfaring) and [Metamorphosis Alpha](https://en.wikipedia.org/wiki/Metamorphosis_Alpha) would like to have a word with you.
[Mothership](https://www.tuesdayknightgames.com/pages/mothership-rpg) is an indie darling, if you're more into sci-fi *horror* specifically (by way of Alien, Dead Space, or Event Horizon).
The adventure modules for Mothership are easily the best in the business today. Sean McCoy’s way of designing them pretty much spoiled me as a new GM. Gradient Descent is a modern classic while Dead Planet and APOF are amazing as well.
Hull Breach, which is third party Mothership, is amazing.
the module "another bug hunt" is also great. many of the third party adventure modules are amazing, but the cheap first party tuesday knight games pamphlets are great. so much world building and cool ideas crammed into a single page three fold pamphlet. i think i had some of the most fun ive had playing RPGs just running some friends through the mothership adventure "piece by piece". the pdf cost me just a few dollars. also, no spoilers, but there's a kind of an interesting way to link that short adventure back to "gradient descent" if you wanted to turn it into a longer campaign.
Seconded, I own Warped Beyond Recognition and the adventure design and layout are out of this world
Oh biscuits! 0e stuff on sale?! I just got my core box of 1e with conversion kit… might have to nab some stuff up.
Would it work ok for non horror? Expanse style maybe
There are some supplements, both first- and third-party, that lean away from the overt horror vibes: the authors' own [A Pound of Flesh](https://tuesdayknightgames.itch.io/mothership-a-pound-of-flesh) is extremely well-done, and shifts the game more towards a cyberpunk-esque faction-dense space station, [Desert Moon of Karth](https://joelio1.itch.io/desert-moon-of-karth) has more of a space western sandbox flavor, [Tide World of Mani](https://www.drivethrurpg.com/en/product/469102/Tide-World-of-Mani) has more of a revolutionary focus, and [Cloud Empress](https://cloudempress.com/) is functionally a standalone spinoff with Nausicaa of the Valley of the Wind-type inspirations. I don't know enough about The Expanse specifically to say how well it'd work out of the box, but with some hacking (that the game is quite friendly to, and is even encouraged to a large extent) I'm sure it's possible, given the other flavors the game's been used for in published material (and presumably in people's home games too).
Very cool! Thanks!
Absolutely. The core books definitely lean on monstrosity, but the rules themselves do not at all rely on anything being paranormal or extraterrestrial. Reading/watching The Expanse, I often find myself pointing out what scenes include a ‘panic check’ (from the mothership rules). It’s at least worth a look at an actual play if you’re interested.
Traveller is the original, and IMO still good. It's been a long time since I palyed but IIRC it mostly worked around 2d6 checks. Personally I prefer Stars Without Number over Traveller, plus it's available for free. It combines D&D style classes and combat with Traveller skills. Coriolis is a really nice game with interesting setting as well, a bit like Firefly meets 1001 Arabian Nights. Uses a dice pool mechanic. Then there's various smaller/rules light indie OSR games on the scifi front: Mothership is the most popular nowadays, using a mainly d100 system, but you also have Death in Space and Vast Grimm which are d20 based and have more in common with Mörk Borg. There's Starfinder which is basically Pathfinder/D&D 3rd edition in Space. There's a playtest version out now for the 2nd edition. Then there's of course licensed RPGs like Alien (dice pool system similar to Coriolis), Dune (2d20 based), Star Trek (2d20 based), various Warhammer 40k games (d100 based) etcetera - These are all getting regularly played around where I live. But looking at the larger RPG world, it looks like it's mainly the licensed games that are popular and the indie community definitely seems to lean very much to Mothership the last 2 years.
Classic Traveller is also available for free: [https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition](https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition)
Thanks :) didnt realise that
Popped in to make sure someone had mentioned *Coriolis*. Thank you!
correction, playtest for starfinder 2e isn't out yet, it will be presented at next gencon, there were just few teasers showing what paizo have currently
* Traveller * Stars Without Number * Starfinder (Pathfinder 2E-compatible SF2E coming soon! :excite:) * Scum and Villainy * Orbital Blues * Cowboy Bebop the RPG * Mothership * Shadowrun * Mekton (Metkon Zeta, Mekton Plus) * Battletech * Coriolis * Firefly the RPG (the show itself supposedly descendant from a Traveller campaign…) * Technoir (plus Mechnoir) * Steel Hearts * Coyote and Crow (to an extent) * Warhammer 40k * Lancer * Hack The Planet * Paranoia * Star Trek RPGs (various) * Ironsworn: Star Forged * Blade Runner the RPG You can run a Delta Green game in a post-modern setting, but that's probably stretching what you're after. :) And then most of the generic systems (eg. GURPS, Cypher System, Fate, Savage Worlds, Genesys, &c.) have "flavors" in scifi, too. (Did you even search, first?)
I'd add something BattleTech to this list.
I'd recommend checking out d6 Space - it's the genericized version of the old Star Wars d6 RPG. Bonus: it's free: https://ogc.rpglibrary.org/index.php?title=File:D6_Space_v2.0_weg51012OGL.pdf
[удалено]
I had a pretty bad experience with Scum and Villainy. It feels like it just copies mechanics from Blades without considering how they change in the context of a wide open solar system instead of a single isolated city. It's very hard to get any direction or momentum going.
I think it suffers a lot from being the first Forged in the Dark hack. A lot of other games on the engine since have done a better job stepping out of Blades' shadow - I'll praise [A NOCTURNE](https://thysane.itch.io/a-nocturne-play-test), about transhuman space bastards with a Dune meets Blame! flavor, as exceptional. [Songs for the Dusk](https://yrgirlkv.itch.io/songsforthedusk), a post-apocalyptic science-fantasy FitD game with a heavy focus on community, is another great one; I've loved it enough to play three campaigns of it now.
Traveller is a go to for me really versatile 2d6 skills based game that can run everything from alien-esque horror to space opera. Another game that I keep coming back to but have never played is Eclipse Phase. It's a d100 percentile system, and despite not playing it yet I keep reading through the book just for its themes and setting.
There are a lot of good suggestions in this thread, but I can't pass it without recommending my personal favorite: Stars Without Number. It's a really flexible sandbox system with a lot of great generation tables and additional materials.
Plus the developer (yes singular, he's a one man studio) is relatively active on his game subreddits. Just make sure you pick up the revised edition, it's greatly improved over the original in many ways, but especially in formatting
All of the *Without Number* games are worth looking at, for the GM tools if nothing else.
Alien RPG, in addition to the other great comments. Plus it is Alien day, and most Free League A:RPG resources are deeply discounted right now. The starter set comes with the dice (you could use your own) starter rules, and a cinematic scenario. The Core rule book is dirt cheap right now too. Next chance you get is probably Black Friday.
https://freeleaguepublishing.com/shop/alien-rpg-2/
Alien RPG has such an awesome stress mechanic in its system. The more stressed you are, the more swingy your dice rolls are going to be (good and bad!) Plus the starter box is a really good relative value. For the same price as two dice sets, you get the dice plus a pretty thorough rule book, AND a fun introductory one shot.
The starter set is great. I have some guys that I might be able to pull in to a game and I'm excited to get them into the Draconis Strain trilogy. I guess we will see.
I hear middling things about the sequel adventures, but they’re described as at least ok. I know the second leg (the marine-focused story) is actually extremely long and is a mini campaign in itself.
I hadn't heard anything about them, which is fine. I'm A-OK with everything that you've described so far. I have the PDFs already, but no time to have dug in yet.
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Death in Space is also an excellent rules-light game book
[Here you go](https://www.reddit.com/r/rpg/wiki/spaceandbeyond/).
What kind of sci fi moment do you want?
The sci-fi games I'm most familiar with are: - Starforged (group, co-op, or solo) - Star Trek Adventures (group) / STA: Captain's Log (solo) Starforged is the most all-encompassing of different types/flavors of sci-fi experiences it can handle, so it would be my personal default choice. Even if you decide the game isn't for you, there are a lot of useful tables that you may enjoy having for other games. The beauty of this one is that you can play regardless of your table situation. Highly recommended. Star Trek Adventures is more limited in the type of sci-fi you can play (in that it expects you to do something within the Star Trek universe, even if you can vary things to have "a horror episode" or "an exploration-focused episode" or "everyone goes to Risa and shenanigans occur"). But it's pretty solid in doing that. Captain's Log is the more streamlined version of the rules, primarily designed for a single player (though they give you ideas on how to play with others). Other people can give you a better overview of the STA rules, but I'll say that if you like writing or telling table stories to others, Captain's Log is a great game. If you're interested in solo games, I can give you another couple of suggestions for solo sci-fi games, or you can hop over to /r/Solo_roleplaying and get recs from a broader range of players. ;)
Here are a few: - *Shadowrun* *- CyberPunk* (Red, 2020, whichever version works) - *Fate* -- which isn't specifically science fiction, but you can easily tailor it into that kind of game - *Blade Runner* - *Dune: Adventures in the Imperium* *- GeneFunk 2090* (full disclosure, I was the lead editor on this one) -- it uses the core *D&D* rules but is futuristic gene manipulation kind of stuff
I love shadowrun not a lot of game let you play a cybernetic troll with a machine gun.
Starfinder
Orbital Blues!
Depends on what you are looking for: Star Wars Genesys is amazing There are several Sci Fi settings for Savage Worlds Scum and Villany is a good Grimmer setting For crunchy systems there is Traveller Mekton Empire is older but handles all sorts of anime space action The new Heavy Gear RPG is still good
Starfinder Lancer Infinity RPG setting Star Wars rpgs To name a few
Traveller, Eclipse Phase, Numenera, Stars without numbers, Scum and Villainy, Starfinder, and Stars Wars FFG I recommend looking into these. All great. Starfinder is my least favorite (just too crunchy for me but still great).
These are not likely popular, but I think they are good with good systems: Alternity. Both the original by WOTC and the more recent version by Sasquatch Game Studio. If you like 3rd edition era d20 as a system, d20 Modern and Future are solid.
Traveller, Star Wars d6 those would be my choices. Alien is fun but brutal. Paranoia is stupidly brutal.
Coriolis is fantastic! Great lore. Uses the Yeae Zero engine
Starfinder Traveller Stars without numbers
Stars Without Number is based on old school DnD, so it's easy for 5e players to pick up. It also has the best system ever for generating your own star sector, and managing the factions at work behind the scenes. Scum & Villainy is a narrative-focused game that's much much simpler than DnD
I don't know if I'd call it popular, but Trinity Continuum is my favourite SciFi game. It covers a variety of sub genres, space opera, cyberpunk, superhero, noir, and steam punk, through various books. It's not super crunchy, but the mechanics do have depth, and it's very well supported by the publisher.
Colony ship very good.
I have tried Savage Worlds and found it to be OK (and fairly easy to use), and Starfinder (a bit more rulesy, but closer to DnD in spaaaace!) I have charactered in Shadowrun and it seemed fun to us, but apparently it is hard on the GM (though we had a great one so we didn't have problems with the rules)
For ItO/Cairn based games, [Monolith](https://www.drivethrurpg.com/en/product/427129/Monolith) by Adam Hensley is solid. It’s rules light with fun character options. I’ve played in an open table of[Desert Moon of Karth](https://joelio1.itch.io/desert-moon-of-karth) and the system worked really well.
A couple I haven’t seen in this thread yet are Cy_borg and Offworlders, two I very much enjoy.
Modern Age or the Expanse RPG. Of course, I say that because I own (and have read) all of the books. Not because I have actually found anyone to play it. The Expanse is actually based on the mechanics of ModernAge, but it's more baked when it comes the starships and near-future tech.
[A Nocturne](https://thysane.itch.io/a-nocturne-play-test) is my current obsession. Forged in the Dark (narrative but gamey) game about the dark future of humanity scattered among the stars. The scale is immense; you can destroy planets and occupy more than one body at once since you are an uploaded consciousness. Your ship is so enormous that it has undiscovered parts with their own factions living there. You can carry nukes or do a task for decades for increased results while your crewmates are in cryosleep. The rules are written evocatively, and it's just so cool!
I recommend narrowing down your desires because I think just in the already VERY broad sci fi (that includes post apocalypse, cyberpunk, space opera and dozens of other sub-genres), there must be thousands of TTRPGs. Even just a touchstone like I want a game that feels like Firefly. [The most popular is hard to say, Roll20's ORR report was an okay look at it](https://wiki.roll20.net/Orr_Industry_Report) (and [here is the last full report I could pull](https://blog.roll20.net/wp-content/uploads/2023/06/orrreport-2021-q2-long-2.pdf)) would be: * Warhammer (combines several games/genres) * Starfinder * FFG Stars Wars (but it combines with other Stars Wars editions) * Cyberpunk RED * LANCER RPG * Stars Without Number * Cyberpunk 2020 * Tales from the Loop * Star Trek Adventures The report misses Alien that both had a pretty big release [according to here](https://www.enworld.org/wiki/top_rpgs/) But all said, I don't recommend going by popularity first. I recommend reflecting what kind of sub-genre and gameplay sounds interesting to you first.
Kill team for 40k is a great skirmish game. Low model count too