What is it?
"The Goo is the cancer of Atys. Atys is an organic planet and you'll have to discover in the game how it was populated and by whom. And... (you'll go play to find out). but Atys has a problem, it has a kind of cancer called Goo by the homins."
"The Goo is a serious matter and there are sources of Goo appearing and invading civilizations' territories. It will have to be pusehd back, otherwise creatures become ill too and more aggressive and their stats increase. And... (you'll find out in the game)
"
http://sor.warcry.com/index.php/content ... _april.php
Where did it come from?
No idea, I assume it's always been there.
What causes it to grow?
No clue, not enough in game to really figure this out yet.
How can it be pushed back?
No clue, not enough in game to really figure this out yet.
Why is it that only the jungles of Zorai are bordered by the goo?
No clue, not enough in game to really figure this out yet.
Is it possible to become resistant to the effects of goo damage?
Not as far as I can tell. Invincibility doesn't even work on it.
Why are all the goo-affiliated tribes anti-Zorai and anti-kami?
My guess is that the Karavan don't see the goo as a threat (as they really don't care about Atys, just it's resources).
The thing to remember at this point is that there really is almost no content or story stuff in game. None of the tribes give information, so it's not possible to learn about the goo yet.