The Monomyth, or at least, that word specifically, was redefined by Joesph Campbell in his work, The Hero with a Thousand Faces.  Campbell analyzed and discovered a consistent pattern in ancient religious stories and myths from across the world.  This narrative framework of the Monomyth, or The Hero's Journey, contained certain stages that Campbell identified in everything from Greek Tragedies to Siddhartha. 

The number of modern works that use some, if not all, of this framework is legion, but most notably, gamer-related films such as Star Wars and The Matrix follow the Monomyth framework faithfully, and novels such as Ender's Game, certainly increasing their popularity by providing a well known and beloved foundation that viewers have come to expect in their dramatic or adventure-themed entertainment. 

Games are not above using the Monomyth, knowingly or not, and can be experienced in games as diverse as Max Payne, The Legend of Zelda: The Ocarina of Time and Half Life 2.  While the narrative structure of the Monomyth provides a strong foundation for game narrative, it should be considered the beginning of narrative structure, and not the end.

The Monomyth structure certainly provides a proven, working narrative structure for a game story, as long as the game story follows the established tropes, in the established order.  The seventeen steps outlined by Campbell certainly doesn't bear repeating here. 

The framework that Campbell explicitly outlined is a fantastic framework for writers and designers, good and not so good, to use as a starting point from where their story flows.  Players will understand the tropes, as they have experienced the major points from a very early age, and understand at an unconscious level how the story is progressing with very little explanation from the writer or designer.

The Monomyth can be experienced in games, as well.  The most shining example of this would be Half Life 2 (sans the Episodic Content). From The Call To Adventure established by The G-Man setting the stage of the world, explicitly telling the player "The right man in the wrong place can make all the difference in the world", to the Teleporter accident forcing Gordon to Cross The First Threshold. 

One could take the story of Half Life 2 and explicitly map events in the game to Campbell's structure and at once understand why the story for the game was so highly praised.  People inherently get it because humanity has spent centuries training our minds to understand these key moments and the emotional connections they provide.

What the use of the Monomyth does, however, is solidifies authorial control to the developers.  When done right, this isn't a bad thing, as experienced in Half Life 2. And completely removing authorial control from the player is a safe choice.  No Player Authorial Control allows developers to spend less time expanding and polishing the potentials of story and all that entails in terms of content and spend more time focusing specifically on expanding and polishing the gameplay mechanics. 

Completely removing authorial control from the player also means that the develop is consciously abdicating the one thing that makes games unique as a story-telling platform:  player input. 

We are just beginning to see authorial control of the story slowly be eked out to the player, even when embracing the Monomyth.  Depending on your dialog choices, the origin stories and subsequent story arc for Dragon Age: Origins closely - if not exactly - follows the Monomyth.  By giving player choice in how the story unfolds, however, many of the tropes of the Monomyth can be completely missed or undone. 

Dragon Age does this willingly and explicitly by giving the player control over the protagonist (the player) during their origin story, as well as over the course of the campaign by empowering the player to make unique choices in how they interact with the world, providing persistent responses and, depending on your choices, a completely unique experience from one play through to the next.

Bioware has taken the first steps in showing developers and players alike that a story does not need to follow the Monomyth to be engrossing.  Dragon Age has taken the timeless structure of the Monomyth and have used it as the starting point, not the firm guide, of their narrative structure.

Looking at the past is a useful tool to establish good game stories, but we cannot ignore the realities of games as they differ from traditional media.  Completely eschewing the player and their interactivity is only going to continue to marginalize games and prevent their wider acceptance as a narrative format that brings something unique to the creative pantheon of storytelling. 

Games provide a unique opportunity in narrative storytelling - focusing exclusively on how it has always been done is going to lead to stagnation.   We need to use the Monomyth and other classic storytelling tropes as the springboard to find our unique voice, not as the albatross around our necks, dooming our media to the doldrums of marginalization and repetition.