A basic history of the continent of Atheus.
"So's ya want ta know about the maze and the labyrinth? There's a difference, ya know. The maze is more like a, a, puzzle, a puzzle where ya wander and gets lost. An' a labyrinth is more... straight, ai guess, straight with curves, if'n ya gets what I'm sayin'."
-Old Gerald, man in the pub.
The great Wall Mounts have been scaled, or your ship's technology has reached a level in which it is possible to cross the oceans. And when the PCs or NPCs find other people, unknown people, what happens? Carnage.
"Your wall is impenetrable, eh? Its so thick it can withstand 100s of direct hits from any siege engine? I have but one word for you: magic."
What if potions and tonics had negative side effects? Potions of increased strength cause violent tempers, or damage joints. What if potions of dexterity caused tremors, or palsy?
What if they were addictive, and had withdrawal symptoms?
Could someone make a bad batch? No one use the brown strength potion!