For Savage Worlds you absolutely only need the Explorer's Edition.
There are several supplements available. I use the Pulp GM's Guide and the Sci Fi GM's guide quite a bit, but really just to see how the designers of the game build things.
As a player and GM, all you really need to know from the Pulp book is that everyone gets the "Slugger" edge for free. That ensures that you're always "armed," even if you don't have a weapon. In other words, you always have your fists. In the base game, if you fight an armed opponent and you're unarmed, then you take penalties.
Everything else is either standard or me-created...
As for Rocketship Empires, it's a system-less book with some guidelines for building starships and other stuff. I just got it for the world and story...and the wicked art. There are three books in the set:
- Core Campaign
- Spain Sourcebook
- Starship Sourcebook
The only bad news is that a Spain adventure module is several months overdue and Ed (designer) has been MIA for at least a month and is MIA off and on. So, I'm not saying it's an unsupported system, but it ain't looking hopeful that there will be regular stuff published.
Either way, the three books were worth it for me, but you could also come up with your own "1930's in Space" campaign without them without too much work...just depends on how much detail you want fed to you.
