I haven't played Dungeon World, but if you're using "sufficient" the way I think you are, meaning "no creativity or rule interpolation/creation" is required, I find that claim hard to believe. I hear dungeon worlders talking about making up "custom moves," with defined prerequisites and effects, and that sounds like rule creation to me.
Not really. 99.99% of the time, it's just taking an existing move and adapting it. For example, one of my players "upgraded" from tiefling to full on cambion (magically made effectively half-devil) during play. That, to me, meant he should gain new powers, and devils had been established to have teleportation abilities. So I came up with a move that I felt worked with that. I built it using the "pick N from this list, or (N minus 1 or 2) on partial success." This is a standard form used by lots of moves, so it's not really "creating" a rule. That is, here is my Teleport move:
Teleportation
When you
pass through the nether realms to teleport somewhere you can physically see, roll+CHA.
On a 10+, choose 2.
On a 7-9, choose 1.
- You go exactly where you want to.
- Your motion goes unseen in either world.
- Your motion is effectively instant.
On a miss, you still teleport, but it is seriously disorienting, or even dangerous. The DM will tell you how.
And here is a default game move, belonging to the Fighter class, for using physical strength to overcome inanimate obstacles in the world:
Bend Bars, Lift Gates
When you
use pure strength to destroy an inanimate obstacle, roll+STR.
✴ On a 10+, choose 3.
✴ On a 7-9 choose 2.
- It doesn’t take a very long time
- Nothing of value is damaged
- It doesn’t make an inordinate amount of noise
- You can fix the thing again without a lot of effort
As you can see, the structure is essentially identical. I just swapped out the trigger phrase, and picked benefits (or, rather, bad things to avoid) that were relevant to Nightcrawler-style teleportation rather than breaking physical objects so you can explore past them. The only difference is that I added a "what happens on a miss" clause (that is, an explanation for what consequences a player might face for getting a truly "failed" roll.) Many ofher moves do this too, so again not making this from whole cloth, just building a move from a standard mold ans boltong on a standard addon.
It's unavoidable. Players will always want to occasionally try sometime the rules don't explicitly allow, and you'll have to make up a reasonable result or system for producing results. Have I misunderstood you or do you genuinely think that Dungeon World has rules and outcomes defined already for every conceivable player action from plunging a toilet to digging mile-long tunnel?
The problem with your question is that you presume that all rules can only take one form: discrete, individual chunks that explicitly approve of, define, or delimit single acts. And, if that assumption is granted, you are quite correct that no system could ever even hope to be comprehensive, because you would need infinitely many narrow, specific rules to cover even a small range of situations, let alone the dizzying variety of unexpected things players might want to do.
But that assumption is incorrect. There is at least one other shape rules can take, which evades this problem. I don't know if there is any kind of
official term, but
my term is "extensible framework rules." That is, a rule
designed so that, without creating any new content (not even to the limited degree of my Teleportation move above), you can apply
one rule to a diverse and infinite set of situations. 4e's Skill Challenge rules are an example of this. Dungeon World's
Undertake a Perilous Journey and
Ritual moves are other examples (the former being what it says on the tin, expeditions into dangerous territory on land or sea; the latter being the catch-all for producing magical effects that aren't codified as moves or spells.) These structures make a different kind of sacrifice, if one can call it that: they are necessarily slightly more abstract than individual, discrete rules would be, so they can work across a
diverse and non-finite set of circumstances.
A ruleset that employs a mix of both discrete-individual rules and extensible-framework rules
can actually achieve comprehensive coverage, or at least something like it.
I suspect you're going to come back with something that says the GM or the player will make something appropriate up, in which case I'm going to say "that's just GM fiat, a.k.a. Rule Zero, extended to be shared with the players." That wouldn't count as an absence of fiat.
And if the answer is "99.9% of the time you just use an existing extensible framework rule, and the other 0.1% you take an existing rule template and apply it to the current situation," where would that fall? Because that doesn't read to me as being "GM fiat," at least not in any sense of the phrase that I'm familiar with.