There are creatures crawling in your world, some passive, others hating your existence.
Monsters Swallow animals, something possesses the creatures of the overworld.
There is a world that connects the overworld to the Abyss; it is very aggressive, but destroying it is the way to save the overworld.
Invent new devices to destroy the evil creatures and find the core of it all... The Mind Flayer.
Fire.. is the key.
