I'd like the logo to do well on any colour background - it'll be displayed either on the front or the back of books, on game content if I choose to bring the game back into active mode as well as in related Youtube videos about the world.
It should have a magical fantasy feel (how you interpret that is up to you). It's a world with high-fantasy (lots of magic), differing regions, gods and races not found in typical fantasy.
It's really important that the logo also has a space for a tagline, such as a book series' name or a character's name so readers and previous players know what to expect when they're looking at which book to get next. There will also need to be another version that looks the same without that space (if contained).
For examples of self-contained logo designs I love, Google the following:
World of Warcraft: battle for azeroth logo
For a logo where it's mostly text and it's memorable, check out:
Prince of Persia logo
Any questions, please ask. I'm looking forward to seeing what you come up with and am happy to make suggestions if a design is promising.