Since it's trendy right now, a small Granblue Fantasy inspired game/open musebox with a couple crews of skyfarers and a story-plot for anybody interested in that. Using an airship to go from island to island in the sky. Settled on a jamjar style of being brought to the world by a primal beast, and characters interested in going home can learn some Astrals lore in order to figure out how to make it send them back. Characters who are adventurous can just enjoy exploring different islands and getting immersed in the world.

Would need lots and lots of planning for different islands, events, primal beasts, and what they could say about the lore while still giving different options in how to get that information. How to deal with canon GBF characters and who can/can't be apped (and how). Just a lot of work for a setting I'm not sure anybody would be interested in, though I like to pick at it when I have the time.