Undertale

The Undertale universe is a 3rd-dimensional one in the digitechtrine. It is inhabited by two races, Humans and Monsters. The two remained in peace untill war broke out, at which point the monsters were defeated and locked in the lower half of the world, where they created a technological civilisation

Both Humans and Monsters have Souls, but different kinds. Souls are small and buoyant hearts of Mind Substance or Angelic Matter Power Gem, housing Consciousnessians that project them, as well as, with monsters, their Mind Substance bodies.

In an experiment by W.D. Gaster, a hole was punched and a portal formed right into the cage of the Unnamed Blacknss in the Realm of Amon. He himself fell in and was shattered across all existence. This allowed a small piece of the Unnamed Blackness to escape, taking form in the soul of a young child named Chara.

Monsters
Monsters' souls are made of Mind Substance and so are much weaker, but because they have the ability to summon mind substance bodies and projections, their bodies are changeable, and they have the ability to to magic. This also means that when they die, their bodies disintegrate as well as their soul. Monsters come in many types, the most powerful being a goat-person hybrid, which has fire magic.