Games based on works of literature, previously published, and characters from those works. This can include novels and short stories, published in books, magazines, in e-books or even online as text.
If the game directly references content or design from another adaptation of literature, such as a movie, it is no longer considered to be based "solely" on the original literature and is instead based on the new derivative work.
Legendary characters such as Zeus, King Arthur or Robin Hood are based on a loose series of tales and mythology. For that reason, different materials have sprung up with completely different retellings and the characters themselves don't really apply to any particular piece of literature. These should only be included in this category if the game references a specific book, author or story.
Games which merely recreate the "atmosphere" of a certain author or set of stories are not to be included in this category.