Still, when you say "or the referee of the campaign decide" it sounds a lot like a traditional model of RPG play where there's a GM who considers themselves a 'game boss' and decides how to do this stuff.
I realize that is one of the perils of writing tersely. I had a more detailed explanation but that caused its own problems. I found writing tersely and then explaining that I am not assuming that any of the steps are handled in any particular way results in better discussion.
I would call Dungeon World 'zero myth', there is no FICTION that is prearranged and determines whether or not play can proceed in a specific direction. Yes, there's genre, and that includes a bunch of D&D-esque monsters, etc. There's a vast difference between that and D&D, where the GM or a module author makes up ALL of the fiction, and it is completely binding on the characters.
Fiction is one of those terms that hobbyists use in many ways. You will have to clarify what you mean. However in terms of setting the initial pages outlines the different character types and their description paints a specific picture of the world the characters inhabit. The fact that it doesn't go into whether the character will be facing the Mad King of Redgate Keep versus The Evil High Priest of the Hellbridge Temple doesn't change that Baker has a very specific type of setting in mind when writing Dungeon World. This is further reinforced by the gamemaster advice given later. Dungeon World is not an RPG that lends itself to running every type of fantasy setting. But instead, focuses on a narrow range of settings that have a specific feel.
And keep in mind we are talking about Dungeon World specifically not the PbtA framework which powers other types of RPGs which deal with different settings and different genres.
Well, you should play Dungeon World then! This is totally not true. I agree that genre has to be established, maybe other elements of 'color' will be as well in order to arrive at a table-wide agreement as to what sorts of ideas will shape character creation, but 'setting of the campaign' is not needed.
Then a clarification is needed by what I am calling a setting. Again it is meant to be taken expansively not narrowly. A setting is the background of the campaign. Anything and everything that could impact how a player will roleplay a character.
The point of all roleplaying whether it is with a human referee as with tabletop RPGs, collaborative storytelling, refereed by a software algorithm, or adjudicated by the rules of a sport (LARPS), is to pretend to be a character having adventures. In order to have adventures there needs to be a place in which adventures can occur. In order for players to decide what to do as their characters there needs to be a context on which the player can make a decision. All of this forms the setting of the campaign.
What I am calling a setting is not just a list of specific details like the Sorceror Supply Shop is on Regal Street just south of the Square of the Gods in City State. It also the more general assumptions and tropes from which those details are created from. The details of Harn are grounded in the fact that it is a medieval setting with some elements of fantasy and the fantastic.
The procedure that I outlined and claim covers all tabletop RPGs works just fine if the group decides to start the campaign with just general assumptions and tropes and paint in the details later as characters are created and the campaign is played. It also works just fine with campaign where the group is sitting with the entire Glorantha corpus sitting on shelves next to the table.
Thus I stand by my point that the first thing that happens when any type of tabletop RPG campaign is run, is that a setting is defined.
I think you are discounting fundamental differences between DW and trad RPGs here.
Given what I said above, Dungeon World is an example of an RPG that starts out a campaign with a setting that is comprised of no details just assumptions and tropes.
In addition, since the first campaigns of the early 70s the process has always started with "Hey what would be fun to play?" Whether it was a decision by a single individual, the referee, throwing it out to the rest of the group. Or a group just brainstorming ideas until one is reached by consensus. Then the details are fleshed out. What Baker did with PtbA style RPGs is make this process explicit and an expected part of how PbtA style campaigns are run.
As I said, there's no 'step 1' in DW.
Step 1 happened when the group decided on using Dungeon World.
Well, there are really profound differences between DW, played as Baker would play it, and trad D&D.
To answer look at the steps I outlined and what I highlighted
- The referee describes a setting
- The players describe some character they want to play in the setting.
- The referee describes the circumstances in which the characters find themselves.
- The players describe what they do as their characters.
- The referee adjudicates what the players do as their characters and then loops back to #3.
You (and
@pemerton ) are assuming, likely based on my reputation, that all of what I highlighted are handled more or less the same way that Dungeons & Dragons and other similar RPGs campaigns are handled.
I deliberately elected not to expand on what one does to describe a setting, describe characters, describe circumstances, how player describe what they do, and how the referee adjudicate. All of these can be handled in different ways including delegating it to the consensus of the entire group. Dungeon World other PbtA RPgs represent a specific implementation of the above.
These steps I feel represent the minimum one has to do in order to run a tabletop role-playing campaign. A group wants to pretend to be characters having adventures using pen & paper this is what works. There are other broad alternatives but that means you doing something different like playing a board game, a CRPG, wargaming, LARPing, Collaborative Storytelling, and so on. Each of those are fun but have different consideration to make them work.