What is an art bible? - polcamacho/Art-Bible GitHub Wiki

An art bible is a document that defines the art style of the videogame. In other words, it describes every aspect of the game in terms of what will look like, and avoids mixing different types of art in order to be coherent and maintain its quality. This document helps art department understand which direction the art takes and make everybody follow an established line. So, things like color scheme, the user interface or assets creation are specified here.

It is created before the art production by the art director, and after the design document, that establishes the function, the mechanics and the entire experience of the game.

Also, an art bible is important to other departments like marketing, because they can use this document as a part of their strategy, for example to sell the product. So, as it is said, an art bible is not something that can be ignored.