One huge expanse of aetherspace.
Maneuver your ship through the vast aether in The Aether Sea, a Fate world and adventure by Ed Turner. A thousand years of war on Homeworld left it a magically-blighted wasteland, so the elves and dwarves stopped fighting for five minutes and figured out how to leave it behind. Soon everyone took to the vast, empty aether sea. The Royal Hegemony keeps a tight rein on the Spellcaster's Union, and the magic that makes aether travel possible. Play the crew of a little aethercraft out in the deep sea. But you've got bad blood with the Royals, so take jobs carefully and make do with the best magic unofficial channels can provide. Keeping the ship afloat won't be easy. The sea’s a dark and lonely place, and secondhand magic is... fussy. When it works at all.