I've been stalking the site for a while now, looking for ideas for how to try and GM a Rogue Trader group and I have absolutely loved what I've seen so far.

However, while I have the core-rule book I have yet to start trying to collect the many expansion books that have come out after it. I have to ask since budget is a thing to be worried about; which expansion books are absolutely required and which ones can be gotten at a later date/ignored outright?

Hi, what sort of games do you want to run? If it's exploration, or character focused, or focused on conflicts will affect it. Also whether you would consider rewritten module content?

I believe that the general consensus on the stuff for players is Into the Storm, Battlefleet Koronus, and Hostile Acquisitions are the best, with BFK and HA trading places in the order depending on whether the game is more ship-oriented or character-scale, with Faith and Coin and the Navis Primer tending to be less consistent in quality, though sometimes useful.

For the GM, the Koronus Bestiary and Stars of Inequity. Stars has player-oriented things as well, in addition to system/planet generation mechanics, and a basic set of rules for developing colonies.

But, as ever, what kind of game you're aiming for and comfortable with matters.

I was honestly thinking a mix of character focus with exploration and combat thrown in.

I personally have a bit of issue with pre written modules since they don't really allow much freedom when it comes to what sort of character you can make. It's less 'What character do you want to run' and more 'this is what you need to have to not die'.

But I have to admit that I am not against a bit of rewriting in order to turn an otherwise decent story into something a bit more playable. Any suggestions?

As above, great book descriptions and it will depend of the characters your players create.

For exploration, there are 2 ways forward. Stars of Inequity allows you to generate your own systems, giving you a framework to create more detail later on. Edge of the Abyss further details the published sector of space.

Another way to look at is, is which Core Book chapters are most important to your game? I believe that each chapter has a book that expands upon it. For example, if space combat happens a lot, Battlefleet Korunus. if the Players are wanting more options, Into the Storm is a large book for them and you. enjoy!

As a player you want:

Core

Into the Storm

Battlefleet Koronus

Hostile Acquisitions

Faith and Coin

Navis Prima

For GM's:

Stars of Inequity

Koronus Bestiary

I know thats a lot of money to sink into the game. But it is so nice having physical copies to flip through.

well I would say Battlefleet Koronus is very useful same with into the storm I personal didn't find much of use in hostile acquisitions or faith and coin the bestiary is very useful for a GM , stars of inequity's rules for systems I found to be not great so I have always had to modify them

Thank you all for the advice. I'll have a look and try to get what I can when I have the time and money.

Hopefully I'll be able to be a decent GM once I've got a bit of information to work with.

Personally, I buy every book. Did it with DH, OW, RT, Warhammer Fantasy 2nd ed...hell, even got the Tau supplement for RT and the 'same' setting mission for OW as well.

For those who lack space or budget,

Core

GM Kit (if only for the screen and xeno generator)

Into the Storm

Battlefleet Koronus.

You're good to go.

I agree mostly with Braddoc, but I really feel that as a GM you need to get the Koronus Bestiary. It's easily my favourite supplement, the linking text in the entry for each of the entries can easily be spun into a mini adventure by the GM, and it offers so many different horrible things to throw at your characters. The enemies can actually challenge the power level of Rogue Traders, and you can quickly create a random creature when you land on an alien world.

So my essential choices are

Core

Into The Storm

Battlefleet Koronus

Koronus Bestiary

I'd save some $$ and purchase some pdfs from drivethrurpg.com.

If you HAD to only get ONE book, I would say Into the Storm, it has good GM and PC tools. It is the one, absolute must buy with the core IMO.

To me, it's actually more important the GM have material than the players.

1. Edge of the Abyss - The book is FULL of story seeds. If you're good at story seeds, then you don't need this.

2. Koronus Bestiary - Great book

3. BattleFleet Koronus details spaceships some more, and introduces broken mass combat on the ground. It is handy to have more ship options available.

4. Hostile Acquisitions.

Looks like noone mentioned my favourite book: The Soul Reaver. Other than that, I kinda agree with the others.