I'm digging this thread too.
To better help my game's needs, here's the general set up. Whereas many worlds are created by gods intentionally, this world's creation was accidental. This is a strange mix between actual astrophysics and the magical. In an unseen part of the multiverse, an eternally slumbering god lay dreaming when a star went supernova. The star collapsed, but the debris was shaped by the dreams of the sleeping god into dozens of worlds. The people of her dreams became real, and while most of the worlds decayed when her dreams shifted, one world actually formed around her massive celestial body, allowing it to endure long enough for the confused people born from her dreams to create societies of their own.
But this new world is imperiled. Though it is kept warm by the ambient heat of the nebula created by the supernova, its orbit is unstable, and it crosses paths with dead planets that blossomed and died with the sleeping god's imagination. Already the world is wracked by celestial catastrophes every few years, and soon the whole world will be torn apart, dissolving back into dream.
The plot of the campaign will have several stages, starting at local mysteries within the PCs' home town, which tie into threats from the outside world caused by powerful beings claiming to be gods, which reveals what true danger the world is in, for if the god who dreamed them into existence dies, they will cease to be.
I don't exactly know how I want it to work, but the PCs will be in a position to use something called The Scroll of the Gods to bind other gods to their world, which will grant them the power to re-align the 'solar system' their world exists in so that their planet isn't torn to bits by the tidal force of a neutron star.
I don't really want the PCs to become gods themselves, though (at least not all of them; it might be cool if one of them does). I want them to find other beings, and raise them from being merely worshipped or revered to being true gods. Maybe they'll learn that gods can reshape reality, so they need the loyal will of several gods to affect change across an entire solar system. Also, the plane will be suffering from the assault of demons and devils who see it as a new battleground for the Blood War, which means the PCs will want to find a way to keep extraplanar nasties off their homeworld.
I like the idea Shades of Green presented, that most 'gods' will be perceived intangibly, and that mortals simply won't understand many of them. This might be a disincentive to the PCs becoming gods themselves. They'll know that the world needs to be saved, but also that, if they do the saving, they'll cease to exist as they are. Other 'gods' than the ones the PCs create will exist, but only the ones whose names are on the Scroll of the Gods will have the power to reshape reality.