I am going to explain here some of the system mechanic, souls ranking, other races and so on.
Let us start with the system basically, you feed the system souls and you can create anything with it. Of course the more powerful and complex the thing you want to create, the more souls you need and for some things like to create life you need the highest quality souls.
Soul's quality:
Low quality souls- regular human or demon.
High quality souls (corrupt or noble)- human's that did extremely good or terrible acts all their life, high ranked demons.
Evil or Holy souls- demon lords, true angels.
Highet quality souls- demon king, seraph, and gods.
Demon ranks:
Low rank- low middle high peak
Middle rank- low middle high peak half-step
High rank- low middle high peak
Demon lord-?
Demon king- seven deadly sins, Lilith, others.
Angels ranks:
Artificial angels- low to middle rank demons
Two winged angels- angel archangel principality (middle rank demon)
Four winged angels- power virtue dominion (high rank demon)
Six winged angels- throne cherub (demon lord) seraph (demon king)
*Demons have more numbers than angels, but angels are stronger in comparison to demons on the same rank, due to holy magic.
The abyss- the true home dimension of the demons, its size is incalculable.
The abyss is divided into:
The upper abyss- the level with the most demons.
The middle abyss- middle rank demons are considered the true warriors of the abyss.
The lower abyss- the commanders and managers of the demon race. Every high demon has his own territory and castle.
Shatter worlds- the demon lords control a piece of land that its borders connect to other pieces of land.
???- the demon kings level of the abyss is a mystery.
Garden of Eden- the true home dimension of the angels.
Gate of the abyss or heaven- portals from the abyss or heaven to travel to other worlds in the multiverse.
Word will- the word will reject all alien demons and angels a like, the only way for them to stay in the world is for them to sign a contract to let them stay for a period of time.
Purgatory space- a space bubble outside the main world that other races can live in like heaven or hell.
If you have any questions ask me in the comments.