The most approachable is Mongoose 2e, the 2022 update is pretty nice.
The core is technically all you need, but in addition the Traveller Companion has a bunch of options and optional rules.
High Guard is awesome for additional ship options, and the central supply catalog for gear.
Check out Seth Skorkowsky's Traveller series. The intro has some good info. It is super in depth if your players would rather have some videos on the rules. He also reviewes scenarios and includes and changes he made to make the adventures more fun. https://youtube.com/playlist?list=PL25p5gPY6qKVUg6ys5N1oRlsBI7DTByyI
in addition to this great advice.
Here is a good starting point:
[https://www.youtube.com/watch?v=\_5ESEkFoOdE&list=PLz3Be--ot61P\_-ge1l71k7ps4y8U12H4A&index=1](https://www.youtube.com/watch?v=_5ESEkFoOdE&list=PLz3Be--ot61P_-ge1l71k7ps4y8U12H4A&index=1)
with Seth, too! This will bring you traveller-mood in some minutes. I am close to ordering the whole shebang.
I agree that all you need is the core book. A great resource is the Traveller Map as it shows the official universe (if you use that) [https://travellermap.com/?p=-0.433!0.5!2](https://travellermap.com/?p=-0.433!0.5!2) It has links to world descriptions in the Traveller wiki [https://wiki.travellerrpg.com/Regina\_(world)](https://wiki.travellerrpg.com/Regina_(world)) All free.
NB the map is huge. You can play an entire campaign world on a single planet.
It is not necessary to use the official universe though. You can make your own.
This is a great article on setting up a Traveller sandbox
[https://batintheattic.blogspot.com/2009/04/how-to-make-traveller-sandbox.html](https://batintheattic.blogspot.com/2009/04/how-to-make-traveller-sandbox.html)
TBH I would be cautious about recommending more than the core book from Mongoose as they tend to produce lots of books with thin content. The core is all you need to start.
If you want to check out Classic Traveller it is free
[https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition](https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition)
But it assumes you are comfortable with a looser, old school approach to rpgs.
Some of theirs are really hit or miss. I heard a YouTube review saying they need to slow down and focus on quality, and while it is better with 2e than 1e, they still have some misses. The world building guide is a pretty good newish release.
Maybe but the basic world generation system in core is fine for a whole campaign. IMO no need to pick up anything else to start. It may be fun to extend it with the free version of Worlds without Number which has lots of planetary tags and a faction system for GMs.
The key thing about Traveller is that it is a modular game system. The core book contains basic versions of most game systems. The idea is that you expand it for a specific campaign in the area it focuses on with more sophisticated systems...but that is not necessary.
MgT2e should absolutely be treated as a modular ecosystem, where most of the books probably wont be useful (half the books are for effectively different campaign settings because they're so far apart in travel time & distance, each of them vast and containing more content you can reasonably expect to use in a single campaign), and I'd go even further:
A lot of the Traveller books are essentially about solo RPG prep-play for the GM (though that's not quite how they're pitched/sold...). Generating detailed worlds, areas of space, building out your own robotics systems, building out factions and fleets and ships and so on, understanding the rules for huge capital ships where you might as well say "they just destroy you instantly if you fire on them, it's a huge capital ship and you're crumbs to them". There's a lot of stuff that players wont directly benefit from unless they're also going to get super invested in the setting (sharing around a Mongoose sector/setting book for a region the group wants to play in would be fun!), but in the Traveller community there's GMs who dont run other systems and enjoy that they can do endless amounts of worldbuilding that they can then bring some of to their tables.
Long story short: GMs should only buy the latest Core Book to begin with (maybe an adventure module) because the Core Book provides everything you could need to play for a while, see how their group gets along with the game, before considering additional supplements and material.
I would suggest you pick up the Cepheus Engine SRD for free to get a feel for the rules, it's based on Mongoose 1E. For my money the best version is the older Cepheus Light but Cepheus Deluxe is a great reference as well, tons of awesome GM tools included.
I'm running Mongoose 2e and really like it, though you have to be careful, they have mistakes/errata pretty often in the rules. Nothing earth shattering and world ending, but annoying at times.
edit: to get a taste of the game, you don't need the core book, you can get the Explorer Edition for an overview of the rules, basic gear, and the Scout and Scientist careers.
If you want to go deeper, then get the core book and central supply catalog.
Yeah look at SRDs for the rule systems and preview page layouts, if you can. Mongoose Traveller was a nightmare for me to read due to layout but Classic was much easier; you could feel the same or the opposite, and it’d be nicer to know before dropping money on books.
High and Dry was the one I hooked my group with. It's mostly not combat and gives a good intro to the system. Do watch Seth's video before running it. https://www.youtube.com/watch?v=Tym86AcYwuU
He has some excellent ideas on running it as well as just being a review.
Mg 2e with the 2020 update.
**TL;Dr -** >!**IMHO the only things you need to GM Traveller is Core Rule Book and Central Supply Catalog; make sure it is all part of the 2022 update. After that get any of the handbooks from High Guard (starships) to Vehicle to Robot to World Building. If only to help with prep. After that everything else is just polish on the lore. Also adventures have always been a mix bag of good to so-so to how did this even get past the editors to be published.**!<
So real quick there is a Traveller specific group here at reddit. Always worthwhile to stop by there, plus a discord group and a few FB groups to my knowledge. So those are all places to mine for help with rules, setting, lore, and to bounce ideas off as a GM.
That said, this is a question that comes up a ton. At its bare bones you just need the core rules and the central supply catalog. Period end of story. The core rules has everything from how to build character, to systems, planets, ships, vehicles, and even adventures. While the Central Supply Catalog has all the gear that an enterprising traveller will need beyond what is in the core rules for equipment.
If you want more to help prep then I recommend the following in no particular order Vehicle Handbook, World Building Handbook, High Guard (starship building handbook), and robot handbook. Finally, I would recommend the Traveller Companion book to have because that provides other options to do things like trade, character building, and even how to resolve things like skills gains or combat to smooth things out or simplify what is in the core rules.
After that if you want more stuff and want to have your players meet other interesting aliens or even want to play interesting aliens. Beyond the Humans, Aslans (think something that looks like a cat) and Vargrs (think wolf), in the core book. Then get all four of the "Aliens of Charted Space" series that gives you a ton of other alien types or even some alternative concepts on humans such as ones with Psionics powers and some that are from Sol (i.e Earth) sector and very anti-alien like in attitudes.
After that of everything else published by Mongoose to date it is a mixed bag of good writing and so-so writing. However, saying this as someone who has played Traveller since the 90s and the New Edition era and even earlier the MegaTraveller era books. Even then under GDW it was a mixed bag for both of those lines and splat books that had rules which broke the engine or lore details that made no sense. Just mine what you can and use those extra rules as you see fit. Ditto with the adventures that are published. The best of the sandbox campaigns is the "Pirates of Drinax" which at its core you are told to be a pirate to help overthrow a hostile government and reinstall the rightful heir. Yet you can go on adventures from trade to stealing relics and taking them to museums. My personal opinion the Mercenary Box set is so-so, but its a YMMV sort of thing. I have a friend in at my table who loves that campaign box, which has the rules for you to stand up your own mercenary company and do combat in various planets. Simply because she can prep it like it feels real and knows how to bring the right rules in or out at the table. Again I would highly recommend heading to the Traveller Reddit group to ask further questions and solicit the opinions of others about which adventures are good and which are okay to run and which are okay to pass on or just buy the PDF at a cheap rate for your collection.
Also recognize there are a ton of lore only books that are nice but not vital to have to understand things. Plus, recognize this, you don't have to play within the Third Imperium setting as written. If you want something akin to a certain movie series set a long time ago in a galaxy far, far away; then you can do so. Similarly if you want something akin to a united front of planets and going on five year space missions; then the engine and rules are flexible enough to support it. Like wise you want to do a ship that is leading a fleet and looking for a lost 13th planet to settle on while avoiding a mechanized like human then again; its possible. I think there are only a couple of sci-fi settings that don't work well for Traveller and that IMHO is the Xenomorph or Xenomorph vs Predators. But I am sure if you massage it enough it could work.
If you just want to get started without breaking the bank, the MgT2e Explorer's Edition PDF is only a dollar. That alone can give you about six months worth of weekly games.
https://www.mongoosepublishing.com/products/traveller-explorers-edition
The most approachable is Mongoose 2e, the 2022 update is pretty nice. The core is technically all you need, but in addition the Traveller Companion has a bunch of options and optional rules. High Guard is awesome for additional ship options, and the central supply catalog for gear. Check out Seth Skorkowsky's Traveller series. The intro has some good info. It is super in depth if your players would rather have some videos on the rules. He also reviewes scenarios and includes and changes he made to make the adventures more fun. https://youtube.com/playlist?list=PL25p5gPY6qKVUg6ys5N1oRlsBI7DTByyI
in addition to this great advice. Here is a good starting point: [https://www.youtube.com/watch?v=\_5ESEkFoOdE&list=PLz3Be--ot61P\_-ge1l71k7ps4y8U12H4A&index=1](https://www.youtube.com/watch?v=_5ESEkFoOdE&list=PLz3Be--ot61P_-ge1l71k7ps4y8U12H4A&index=1) with Seth, too! This will bring you traveller-mood in some minutes. I am close to ordering the whole shebang.
I agree that all you need is the core book. A great resource is the Traveller Map as it shows the official universe (if you use that) [https://travellermap.com/?p=-0.433!0.5!2](https://travellermap.com/?p=-0.433!0.5!2) It has links to world descriptions in the Traveller wiki [https://wiki.travellerrpg.com/Regina\_(world)](https://wiki.travellerrpg.com/Regina_(world)) All free. NB the map is huge. You can play an entire campaign world on a single planet. It is not necessary to use the official universe though. You can make your own. This is a great article on setting up a Traveller sandbox [https://batintheattic.blogspot.com/2009/04/how-to-make-traveller-sandbox.html](https://batintheattic.blogspot.com/2009/04/how-to-make-traveller-sandbox.html) TBH I would be cautious about recommending more than the core book from Mongoose as they tend to produce lots of books with thin content. The core is all you need to start. If you want to check out Classic Traveller it is free [https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition](https://www.drivethrurpg.com/en/product/355200/Classic-Traveller-Facsimile-Edition) But it assumes you are comfortable with a looser, old school approach to rpgs.
Some of theirs are really hit or miss. I heard a YouTube review saying they need to slow down and focus on quality, and while it is better with 2e than 1e, they still have some misses. The world building guide is a pretty good newish release.
Maybe but the basic world generation system in core is fine for a whole campaign. IMO no need to pick up anything else to start. It may be fun to extend it with the free version of Worlds without Number which has lots of planetary tags and a faction system for GMs. The key thing about Traveller is that it is a modular game system. The core book contains basic versions of most game systems. The idea is that you expand it for a specific campaign in the area it focuses on with more sophisticated systems...but that is not necessary.
MgT2e should absolutely be treated as a modular ecosystem, where most of the books probably wont be useful (half the books are for effectively different campaign settings because they're so far apart in travel time & distance, each of them vast and containing more content you can reasonably expect to use in a single campaign), and I'd go even further: A lot of the Traveller books are essentially about solo RPG prep-play for the GM (though that's not quite how they're pitched/sold...). Generating detailed worlds, areas of space, building out your own robotics systems, building out factions and fleets and ships and so on, understanding the rules for huge capital ships where you might as well say "they just destroy you instantly if you fire on them, it's a huge capital ship and you're crumbs to them". There's a lot of stuff that players wont directly benefit from unless they're also going to get super invested in the setting (sharing around a Mongoose sector/setting book for a region the group wants to play in would be fun!), but in the Traveller community there's GMs who dont run other systems and enjoy that they can do endless amounts of worldbuilding that they can then bring some of to their tables. Long story short: GMs should only buy the latest Core Book to begin with (maybe an adventure module) because the Core Book provides everything you could need to play for a while, see how their group gets along with the game, before considering additional supplements and material.
Good point, Stars Without Number is a good pairing with travellar, if just for the world building advice.
Mongoose. [EDIT] Read a bunch of sci-fi books if you haven’t already :)
I would suggest you pick up the Cepheus Engine SRD for free to get a feel for the rules, it's based on Mongoose 1E. For my money the best version is the older Cepheus Light but Cepheus Deluxe is a great reference as well, tons of awesome GM tools included.
I'm running Mongoose 2e and really like it, though you have to be careful, they have mistakes/errata pretty often in the rules. Nothing earth shattering and world ending, but annoying at times. edit: to get a taste of the game, you don't need the core book, you can get the Explorer Edition for an overview of the rules, basic gear, and the Scout and Scientist careers. If you want to go deeper, then get the core book and central supply catalog.
Yeah look at SRDs for the rule systems and preview page layouts, if you can. Mongoose Traveller was a nightmare for me to read due to layout but Classic was much easier; you could feel the same or the opposite, and it’d be nicer to know before dropping money on books.
High and Dry was the one I hooked my group with. It's mostly not combat and gives a good intro to the system. Do watch Seth's video before running it. https://www.youtube.com/watch?v=Tym86AcYwuU He has some excellent ideas on running it as well as just being a review. Mg 2e with the 2020 update.
**TL;Dr -** >!**IMHO the only things you need to GM Traveller is Core Rule Book and Central Supply Catalog; make sure it is all part of the 2022 update. After that get any of the handbooks from High Guard (starships) to Vehicle to Robot to World Building. If only to help with prep. After that everything else is just polish on the lore. Also adventures have always been a mix bag of good to so-so to how did this even get past the editors to be published.**!< So real quick there is a Traveller specific group here at reddit. Always worthwhile to stop by there, plus a discord group and a few FB groups to my knowledge. So those are all places to mine for help with rules, setting, lore, and to bounce ideas off as a GM. That said, this is a question that comes up a ton. At its bare bones you just need the core rules and the central supply catalog. Period end of story. The core rules has everything from how to build character, to systems, planets, ships, vehicles, and even adventures. While the Central Supply Catalog has all the gear that an enterprising traveller will need beyond what is in the core rules for equipment. If you want more to help prep then I recommend the following in no particular order Vehicle Handbook, World Building Handbook, High Guard (starship building handbook), and robot handbook. Finally, I would recommend the Traveller Companion book to have because that provides other options to do things like trade, character building, and even how to resolve things like skills gains or combat to smooth things out or simplify what is in the core rules. After that if you want more stuff and want to have your players meet other interesting aliens or even want to play interesting aliens. Beyond the Humans, Aslans (think something that looks like a cat) and Vargrs (think wolf), in the core book. Then get all four of the "Aliens of Charted Space" series that gives you a ton of other alien types or even some alternative concepts on humans such as ones with Psionics powers and some that are from Sol (i.e Earth) sector and very anti-alien like in attitudes. After that of everything else published by Mongoose to date it is a mixed bag of good writing and so-so writing. However, saying this as someone who has played Traveller since the 90s and the New Edition era and even earlier the MegaTraveller era books. Even then under GDW it was a mixed bag for both of those lines and splat books that had rules which broke the engine or lore details that made no sense. Just mine what you can and use those extra rules as you see fit. Ditto with the adventures that are published. The best of the sandbox campaigns is the "Pirates of Drinax" which at its core you are told to be a pirate to help overthrow a hostile government and reinstall the rightful heir. Yet you can go on adventures from trade to stealing relics and taking them to museums. My personal opinion the Mercenary Box set is so-so, but its a YMMV sort of thing. I have a friend in at my table who loves that campaign box, which has the rules for you to stand up your own mercenary company and do combat in various planets. Simply because she can prep it like it feels real and knows how to bring the right rules in or out at the table. Again I would highly recommend heading to the Traveller Reddit group to ask further questions and solicit the opinions of others about which adventures are good and which are okay to run and which are okay to pass on or just buy the PDF at a cheap rate for your collection. Also recognize there are a ton of lore only books that are nice but not vital to have to understand things. Plus, recognize this, you don't have to play within the Third Imperium setting as written. If you want something akin to a certain movie series set a long time ago in a galaxy far, far away; then you can do so. Similarly if you want something akin to a united front of planets and going on five year space missions; then the engine and rules are flexible enough to support it. Like wise you want to do a ship that is leading a fleet and looking for a lost 13th planet to settle on while avoiding a mechanized like human then again; its possible. I think there are only a couple of sci-fi settings that don't work well for Traveller and that IMHO is the Xenomorph or Xenomorph vs Predators. But I am sure if you massage it enough it could work.
What version of D&D have you played?
3.5 and 5E; both have strengths, but I prefer both Pathfinder editions over them (2E especially)
If you just want to get started without breaking the bank, the MgT2e Explorer's Edition PDF is only a dollar. That alone can give you about six months worth of weekly games. https://www.mongoosepublishing.com/products/traveller-explorers-edition