Perhaps you had a great idea for a little piece of a setting, you don't have a world, just a fragment, but it inspired you. It might not even have been your own, perhaps you were inspired by another's work. In any case, you have this idea, and perhaps you want to get it out there.
This is not an advice thread on how to build a world, but instead a repository for all those beautiful ideas. Perhaps a world shall be born out of the chaos, or perhaps this thread shall die quietly in a corner, never to be seen again. But this thread is out there for people to share their ideas. Perhaps a world shall rise.
This is for ideas big and small, be it an overarching mythology or a simple tavern, a magic system, a faction, a city, a nation, a history, a plane, in full-fledged description or just a simple line.
In addition, this thread is for ideas of all settings, from pre-historic to post-apocalyptic. Perhaps classic fantasy, perhaps modern dystopic, western, Victorian, action science, space, steampunk, ancient history, far future.
Anyways, this is out there now. I may not frequent the thread very often (if indeed this manages to become a thread) but this was my idea to throw out into the void and maybe it will inspire worlds.
Some of my own, short ideas:
There is a race of angelic beings, though mortal and with no apparent divine connection. Their own legends claim such though and the race primarily consists of scholars who wish to find a philosophical truth, though their methods do vary. While many do ponder idly and live an isolationist existence, there are also many who venture out into the world to discover the truth themselves.
Superstition in this world, a fear of the undead (possibly real, possibly not), has led to a tradition of of crossing a corpse's arms and nailing their hands to their shoulders before burial.
The world suffered an apocalypse (relative advanced-ness of the previous society negotiable). Far from hoarding their secrets, the people of before protected them, but meant them to be found, they had prepared for the doom that was to come. With the discovery of the first of the caches, society enters a renaissance, explorers fervently search for the next trove of information and technology and civilization begins to reclaim the lands it lost.
Clockwork druidry. A mix between the two concepts, druids of this world create magnificent, living constructs, part mechanical, part magic, amalgamations of metal and wood that can channel the spirits of the world and give them physical form.
The magic of this world is a real, tangible, and often dangerous thing. Magic is based on technology, but it is not of technology. Devices exist to collect and channel this energy. If turned into game mechanics, it would essentially create a gear based magic system, with reserves and gradual recharge.