A while back someone asked in a comment about which edition of King Arthur Pendragon to get and where to start with the game.
Here is my delayed reply:
First, the rules don’t change very much at all between editions, though there are a few changes that have solid impact from edition to edition. You could get third, fourth, or fifth editions and basically be playing the same game.
The 3rdedition core rules start the game in Salisbury in the middle of Arthur’s reign. This puts everyone in the middle of a period of Romance and Chivalry, which is what most people think of when they think of King Arthur. So there is an advantage in that. You are either a Cymric Christian Knight or a Cymric Pagan Knight, both from types from Salisbury. One might not think this is enough to differentiate PC Knights… but in fact the Traits and Passions do that job just fine.
There was a supplement for the 3rdedition called Knights Adventurous. It expands the places knights could come from, as well as much more information about the society and culture of the world. For example, there is information about creating a priest or monk, even though the text makes it clear that KAP is a game about playing Knights. So you can have a Knight from additional religions and different lands.
Magic in both editions is in the hands of the Game Master. There are no rules or mechanics for magic. The Game Master simply makes what he wants to happen happen. From the game’s point of view, magic is magical and is not to be understood by Knights and Players alike. It should be strange and mysterious. The Game Master creates magical effects as needed to create wonder and surprise.
The 4th edition took the 3rd edition core book, added the pages from Knights Adventurous, changed the text of these two books in a few spots, and added a system for Magic, allowing the PCs to be Magicians. In general, the game moves away from KAP as a game about Knights into a more general RPG of “People within an Arthurian Setting.” If you want a game more like this, this is the edition for you.
I have never tried to play the game this way, but I am not sure how the dynastic pressure to have children, a general structure of one adventure per session, and other elements of the core game work with Knights, Magicians, and Friars all traveling together. But many, many people are very fond of this edition.
Finally there is the 5thedition. It is the edition I recommend. (Currently edition 5.2). This book starts the players as Cymric Knights in Salisbury, with the option of being Roman Christian, British Christian, or Pagan Knights. The Magic System from the fourth edition is gone. And the game now begins in the years of Uther Pendragon’s reign, before Arthur is even born.
The KAP 5.2 core rules contain an appendix with the equipment and rules changes needed to advance the game into the decades when Arthur rules. But that said, if you wanted to jump into the middle of Arthur’s reign as knights, the third edition would be an easier way in. But that is no longer available in print. Ultimately, you’d get the 5thedition and then make adjustments to the time period you want to play in as required.
Significantly, the core rules plug directly into The Great Pendragon Campaign. The GPC contains notes for running a KAP campaign starting in 485 (before Uther dies) into the period of Anarchy after Uther dies, into Arthur’s efforts to become king, the rule of Arthur, the introduction of Romance and Chivalry, the Quest for the Grail, and the fall of the Round Table.
The GPC also expands on the equipment, costs, and cultural changes through each historical “Phased” of the campaign. A group of players could, if they wished, read up on a specific section and start play in any era they wished.
Thus, here is my summation if you are interested in playing one of the best RPGs ever created:
Get yourself King Arthur Pendragon 5.2 and the Great Pendragon Campaign. With these two books you’ll have enough to keep you busy for years of play.
There are also several supplements available for the 5thedition of King Arthur Pendragon. One of them is the Book of Knights & Ladies. Like the 3rd Edition’s Knights Adventurous it is chock full of notes for building Knights and Ladies from different lands of different faiths.
The entire line of King Arthur Pendragon products has now reverted to Chaosium. (The rights were lost during a turbulent period at Chaosium years ago.) You can pick up a print edition of the core rules, as well as PDF editions of the Great Pendragon Campaign and other supplements here. Each description of each product also contains links to DriveThruRPG for print editions of the products.