Supplement Four said:
I agree. The core rules for CT is the LBBs in their entirety.
But, really, who cares! Is this worthy of discussion?
Actually, it's quite relevant, since Marc seems to be rejecting some of Bk5's tropes in what Robject is posting in the T5 area on COTI.
It goes also to "what is a core ruleset"?
I do feel Bk4-8 are part of the OTU, and that those specific elements (like ranks) that were changed in later editions either are timeline based changes, or are changes to fit the "OTU"...
But the core rules, for any game, are the minimum set, based upon the releasing company's sales model, for playing the game. Books 4-8 are not "Not Classic Traveller", nor is playing without them "Not Classic Traveller". But, playing without Books 1-3 is clearly "Not Classic Traveller".
The relevance comes from certain assertions of "realism" or "attempted realism"... they just don't exist in those 1st 3 books... it is high-space-opera, with passing nods to realism (specifically, vector movement, firearms instead of zap-guns).
Adding Bk 4 changed little except adding an optional CGen, and added lots more weapons. It added an optional style of play, that of the merc unit commander, and a non-detailed resolution system to make that playable. Nothing essential about that.
Book 5 adds another optional CGen, and the most important rules addendum in the whole of CT: the new ship system and its combat system. it was only halfway backwards compatible; old ships could be used in the new combat system, but new ships can't be used in the old combat system. Now, this one is essential to running the OTU, but not to running a good traveller game; in fact, it's often rejected as being even less realistic than the core. (Bk5 Destroyers are the size of a Nimitz class CVA, with crews the size of a cutter...)
Book 6 adds yet another optional CGen, and adds an option to expand the process of detailing star systems beyond the mainworld.
Book 7 adds yet another optional CGen, and adds a different trade system with a whole different paradigm,
Book 8 adds robot rules, far more closely related to MegaTraveller's design system than anything CT. Do they work? Sure. Are they needed to run the game? not at all.
Supplement 4 added a bunch of 12 new careers, and primitive weapons. And it included a bunch of NPC's for each. Needed? No. Useful, yes.
Spinward Marches Campaign added the same 12 new careers. It didn't include the other stuff, and had almost no rules material besides this.
Supplements 1 & 2 were generic "GM Aids"... are they core? Not at all. Useful for running CT? Yes.
Supplement 3 is core to the setting: it's the first official setting booklet. So useful that about 75% of it wound up in the Deluxe Traveller box (The worlds list is in Adv 0, and the map on a poster... and in the Deluxe Box). Is it a core product? Arguable... I'd say it is as close as can be without being one. Mostly due to not being included in the later Starter Traveller.
So what is a core rule set?
Sufficient to run the game. The default "start here point". The "Common Point of Reference". The only parts of Books 1-3 invalidated by later books are starship combat (since B5 grandfathers Bk2 designs) and Trade and Commerce (replaced by Bk 7's system, which to many is inferior and/or simply annoying and thus never used).