From the publisher:
Mystic Empyrean is a vast and unique Role Playing Game that focuses extensively on social character development, world building, and shared storytelling.
Players in Mystic Empyrean take on the roles of Eidolons, beings of power who wear their souls as a skin. Eidolons take a shape granted by their personalities, which alter both their forms and powers. Cruelty may bestow the power to kill with a touch, while Charity can give one the power to create new life from scratch, and Cowardice can cause an Eidolon to shatter like glass when struck.
The Mystic Empyrean Player's Guide contains all the information players need to create Eidolon PCs, grow their world from scratch, and play out adventures within it.