How to go back to world overview in So Many Me?
Solution 1:
Turns out, once you enter the second world, you get a little tip in your screen that says something like this (from memory):
You can now visit "Horizon Ruin" from the x10 Globe
So basically: don't re-enter the first world before you've visited other worlds, so that you do have the option to go back to the world overview from the menu.