You could explain the alternate world as being a flipside of the Foul One's other world.
Aluonra being the good side and Xemorid being the bad side.
After the Foul One collected enough energy to remake the world as it saw fit.
The Foul One corrupts worlds all over, but it using the unusual amount of negative
energy from Aluonra to fuel its corruption in all worlds. So it remakes Aluonra once again,
but this time creates a dual plane.
Think like the yin-yang. One world is light with a seed of darkness and the other is a world of darkness
with a seed of light. Aluonra is the world of light being corrupted by darkness that the Foul One set up to harvest
more energy, but Xemorid is the result of the left over negative energy forcing itself to form a mirror of the light.
The Foul One took residence in Xemorid and destroyed the seed of light turning Xemorid corrupt Xemorid with no chance of redemption.
Now the world of Aluonra is all that matters. The Foul One began to corrupt it as well. From this are born the messengers of the corruption.
Gods have been given the power to teach mortals to break the laws of life and death more easily than before. Chaos is now in reign.
Now, the final hope of this world will take its stand. Dwarves and their never ending thirst for riches and life have established the first new battleground.
They have built a fort. Much like its three brethren before, it acts as a lighthouse attracting the souls scared with the dark to its brightness. But like the forts before, this is exactly what the Foul One wants.
Dark energy comes from the crushing of hopes and dreams... and we all know how easily dwarven spirit can be broken.
The Foul One will challenge our spirit, but we must dig on!
Goblins will raid our homes, but we must dig on!
Vampires will stalk in the corridors, but we must dig on!
Some of us will break, but we must dig on!
Our picks are the picks that shall shatter the very stone upon which we stand! Toward fortune, toward glory, and most of all toward adventure.
As long as we have the spirit to dig, we have all we need to continue to defy the Foul One.
So friends, family, and loyal war hippos I say... WE MUST DIG ON! STRIKE THE EARTH!
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Um... I meant that to be brief, but I really got into it. I have trouble controlling my thoughts at night.
I mostly thought the idea that the Foul One created the new Aluonra as a generator and the flipside
Xemorid as a place for the corruption take permanent hold. Now the world beyond that veil is untouchable.
The game is being played in Aluonra and the happenings of Xemorid don't matter much.
On the name thing, I think "Fail" should still have some part in the name.