The rules of Dungeon World reiterate throughout that the game only works if the rules and the fiction work together. This means that the rules will drive the fiction of the game, BUT ALSO, that the fiction of the game impacts the rules. The attention the system gives to this concept is constant, and you can see how important it is to the designers that the game flows as a natural story that’s not constantly burdened by the chains of the rules.
The system is clear that if someone cuts off your hand – your hand is gone. You should mark this on your character sheet. If you try to climb a rope with one hand, you’re going to have problems doing it, because the fiction demands it, not because there are rules for missing hands. Most people agree that the biggest advantage that table-top RPGs have over any other type of game is the ability of the players and GM to provide a world with texture and options that simply aren’t achievable in video games today. Dungeon World has realized that a lot of strict game systems get in the way of this fundamental power of human creativity, and emphasizes over and over that if the fiction dictates something, that something must be supported then by the rules of the game.
You can see this in the damage chapter, where the rules talk about specific damage (yet GM moves don’t explicitly deal specific damage). You can see this in the character advancement rules related to gaining special moves that aren’t part of your class because the fiction implies that you have learned new moves. The empowerment of the fiction makes Dungeon World quite a bit more narrative focused than classic D&D. Still, one of the most frustrating aspects, to me at least, of recent RPGs (I’m looking at you 4E) is the reduced significance of the fiction for the sake of mathematically sound and consistent mechanics.
From the rules on Character Change:
“Advancement, ilke everything else in Dungeon World, is both prescriptive and descriptive. Prescriptive means that when a player changes their character sheet the character changes in the fiction. Descriptive means that when a character changes in the fiction the player should change the character sheet to match.
This isn’t a benefit or detriment to the players or the GM; it’s not an excuse to gain more powers or take them away. It’s just a reflection of life in Dungeon World.
… Descriptive changes only happen when the character has clearly gained access to the ability. It’s not up to any one player to decide this – if you think a character qualifies for a new ability, discuss it as a group.”
There is a downside to some of this, and some players are going to be thinking it right now. With the fiction in control, and the GM is so in control of the fiction, the players lose some rules “they can count on.” The world begins to shift under your feet a little bit. I can see and sympathize with that point of view. Dungeon World does one other thing though that helps ameliorate that concern. Many moves in Dungeon World allow players a bit more control over the fiction of the game. You can see this influence even in the character advancement rule above. In this way, it becomes even a little bit more like a story-game, but I think it does so just enough to grease the wheels of adventure and file off the rough edges of a vast clunky set of rules that may, or may not, well-simulate a given scenario in the game.
Dungeon World has taken the stance that the game rules, if they are truly going to be simulationist, are going to overwhelm the game play at the table. Indeed there are so many scenarios that are somewhat different that trying to create strict simulationist rules for everything is the wrong way about it. Why not take advantage of the human element of the players and the GM to use the simple framework of Dungeon World’s rules to adjudicate each scenario as it presents itself. And if the basic framework doesn’t well-model the fiction of the game, then the fiction wins anyway and doesn’t have to abide directly by basic framework rules.