I grew up playing a lot of roleplaying games (this was back when they were published as books, rather than boxes full of plasticized crap, and you had to provide your own pencil and dice, not to mention figurines, monster stats on cards, movement distance rulers, initiative chits, etc.). I was the gamemaster a lot, back then, and a big part of the gamemaster's role is world creation.
A big part of what a novelist does -- especially a speculative fiction novelist -- is also world creation.
But there's a difference between the gamemaster's work and the novelist's. The novelist has to create a world that is broken.
What do I mean? I mean that a GM can set up a world that is basically in harmony, in stasis, at peace. Hopefully there are some moving pieces, and things happen off-screen when the players aren't around, but the logic of roleplaying adventure doesn't require it. The players can travel around, digging recalcitrant gnolls out of their warrens and selling their booty in town, in a world that basically works.
But the action in a novel begins with the breaking of the world. It might not be actually the whole world (except in epic fantasy), but the protagonist's world is broken. Something has to be really wrong, to kick the protagonist into action to find a solution. He isn't just trying to find a Sword +2 to replace his Sword +1... his parents are murdered, or his family is cursed, or there is a drought in the land, or the forces of evil are on the march.
In the world that the novelist creates, something has to be badly wrong at the start, or something has to go badly wrong early on (say, first fifty pages)... that's the "inciting incident" that sets the rest of the story into motion.