What's the story you would write if you were an author?
A lot of people worldbuild when they daydream and have the bones of a story kicking around in their brain, but have to pay the bills and raise the kids etc so they never flesh it out and write it down. What's your story's premise? Fantasy, sci-fi, alternate history, mystery, western, whatever genre.
I'd finish one of the stories I'd already started:
Sci-Fi, life on board a converted old interplanetary transport vessel, refitted for interstellar transport, on its way to join a small group of pioneers and colonize a distant planet.
Fantasy, centered around a crafty dwarf who has built a decent self sufficient for himself independent of the fortress, unaware that his childhood friend caught a curse and caused the fortress to succumb to the goblin invasion.
A more down to earth story about a struggling early twentysomething, and what sheer desperation does to a person.
...but the common denominator for all three is that I haven't quite figured out the plot yet.
Typical dwarvish. Very hierarchical. An industrious proud people, full of skilled craftsmen who pull their weight for the greater good of society. Due to seasonal attacks from a goblin horde nearby, they've built fortification that protect them, and during attacks the wall guards are helped by alchemists fire. Unfortunately that last step failed during the most recent attack, which was also unusual in its strength and strategy (the horde got outside help), causing the fortress to fall. While looting, the invaders opened the floodgates that had redirected the river, thus drowning any survivors except one.
I played a fantasy game (on Nintendo 64!) that had a lore waaaay too ridiculously deep for itself, but part of it was that a vaguely dwarvish race had dwindled to a single city via repeated wars and pogroms from other races, and were living under the protection of one of the large human kingdoms at the time. These dwarves were also secretly harboring the last known dragon in the world, who had given magic to humans about a thousand years ago.