Seems that for this fanbase, actual worldbuilding is too problematic :
there are too many conflicting view of how the world should be handled.
And these view shouldn't remove enjoyement from the actual story, which
is the real vision of the world.
Thus do the same as the Sonic Team : let's focus on the ongoing story
and character, and not try to make bold statement about Sonic's world.
Let's work this by being vague about the actual world, and just
mentionning actual places when they are needed, and let people the
possibility to think the island the way they want.
Change thus the motivation of the ennemies from being concerned by a
possibility of an "alien invasion" to being more concerned by the power
of the mobians.