Mine are entirely hobby-based, but I take a bit of pride in it. I've been writing DnD 3.5e campaign settings for a decade now. Most of them are shelved (I'm actively tinkering with involves the inside of a fantasy-based Dyson sphere), but the one I'm currently using is mid- to high-fantasy, based on where you are, with a plotted-out history from the moment the universe started until about three and a half years (in-game time, about a year out of game) after the game started.

While I do have a bunch of dungeons ready for them across various difficulties (across most difficulty spectrums, with increasingly cooler homebrew rewards based on how hard it was to beat), I also have a lot of political intrigue ready. Nation-states, city-states, mountain-states, borderlands, nomadic regions, guilds, enclaves, and people-of-interest who all have some connection to each other in some way (economic, diplomatic, etc). This doesn't include the Outer Planes, which I've made some changes to in order to better fit my cosmology (for example, the Infinite Planes of the Abyss are literally a gaping wound in the structure of this universe. The deeper you go means the further outside of the universe you get, which leads to all kinds of Lovecraftian space-time madness.)

While the players themselves are, realistically speaking, tiny cogs in a pretty big machine, I don't stop them from doing cool shit (in fact, I encourage it.) Even if there's no specific rolls for "I jump from the balcony, grab the chandelier, swing from the chandelier, and kick the guy I'm swinging into", it sounds great and I'll give them a DC based on how hard that sounds. If they have a plan to hijack an airship, attach boosters to it made from bound fire elementals, and then ram it full-speed into a floating fortress belonging to their current antagonist as a way of crashing the whole thing into a volcano, I'm not going to say no (because that's fucking goddamn awesome) but they're going to have to RP out a plan and pass some DCs to make it work.

When I'm done the whole thing I might put the campaign setting into something formal for publishing (right now it's just binders and notebooks), but honestly it's just a hobby I like to do.