Building your own world

an idea surfaced yesterday for a book...an adventure book wherein I create a cast of "otherworldly"  creatures and the world where they dwell.  Writing on paper really helped and now it's time to flesh out these characters, make them individuals with personality and purpose.  To create an entirely new landscape where the characters live their lives.  food, shelter, clothing, the whole thing...anything I can imagine, from the color of their eyes to the size of the oceans and the other creatures who dwell in a world that I have created.   Certainly authors, musicians, painters all experience this, and now the world of gaming.  Dwarves, elves, mages, kings and peasants, dragons and heroes...mind blowing.  And all the technology that can take us there.   It's a wonderful time to be alive.