The main menu is in space and in the background is a timelapse of the world you just played on spinning
Alternative: A completely new planet and on the event that you create a new world, the seed for the main menu planet will be selected
Neptunian: "I feel like having the planet close up at the bottom of the screen, slightly peeking over the atmosphere, with the title at the top and menu buttons to the side could be cool"
How I picture it ^