[Like the radio playing 'Still Alive' in Portal, "diegesis" means music, titles and other effects seen both by the audience and the fictional characters in films -- Gregory Weir examines the concept in LucasArts' Grim Fandango, suggesting it has fascinating applications for games.]
In video games, there is a division between the world inhabited by the game's characters and the representation of that world to the player. The game environment, world objects, and most sound effects and dialogue exist in the game world; that is, they can be perceived by characters.
Other elements, such as most background music, loading screens, and subtitles, exist outside of the game world. They are part of the narration of the game, and help to provide the player with information or emotion that is not necessarily apparent to the characters of the game.
The film world calls this concept "diegesis." This is most easily explained in relation to music. If a film's music comes from a source inside the world of the film, like Casablanca's piano-playing Sam, it is said to be diegetic.
The dramatic music that plays over a James Bond action scene, however, cannot be heard by Bond; it is non-diegetic. Video game music can be looked at in the same way; Super Mario Bros.'s earworm background music is decidedly non-diegetic, but when the player comes across a radio in Portal playing a Latin version of "Still Alive," that music is diegetic. The player character Chell can hear it just like the player can.
Diegesis In Games
The concept of diegesis applies to more than just music, of course. HUD elements can be non-diegetic or, as in Metroid Prime or Star Wars: Republic Commando, incorporated into the player character's helmet and therefore diegetic.
Metroid Prime, in fact, plays with diegesis via the game's very interface. By using the X-Ray Visor, it becomes clear that while the player selects Samus's weapons with the C Stick, Samus herself chooses weapons by moving her fingers into various positions.
One work that pays particular attention to the concept of diegesis is LucasArts's 1998 game Grim Fandango. The game creates a very cinematic atmosphere by dispensing with many non-diegetic elements.
Playing the game feels very much like watching a film noir piece due in part to this decision. By looking at how Grim Fandango handles diegesis, we can see how this concept can be used in video games.
Grim Fandango's Design Decisions
Grim Fandango is the successor to a long line of adventure games put out by LucasArts. All of the company's previous titles use the SCUMM engine, where the player controls the game with a mouse cursor, choosing verbs for the player character from a list or a "verb coin." Clicking on the ground moves the character, and the character's inventory of held items either occupies a portion of the screen or is visible via a secondary screen.
Grim Fandango, however, is based on a new engine. The GrimE engine, as used in this game, has no visible verb list, no mouse cursor, no inventory screen, and no hover text for world objects. Instead of clicking to move the main character, Manny Calavera, the player steers him with the keyboard.
Interactive objects are indicated by Manny turning his head to look at them as he moves. The non-diegetic inventory screen is replaced by a close-up view of Manny's jacket, where he takes out various objects as the player flips through his collection, putting each item away before taking out the next.
This design decision has clear advantages. The lack of non-diegetic screen elements encourages player immersion by making the game world seem less artificial, and the inventory system does a similar thing by ensuring that every player action, even that of searching through the inventory, represents an action taken by Manny.
Additionally, the gameplay looks more cinematic, which reinforces the game's connection to its film noir inspirations. The game almost feels like playing a CGI noir film.
The Downsides Of Diegesis
However, the diegetic elements have their downsides. The movement system is often more awkward than the simple click-to-move approach, and Manny's gaze is a less useful indicator when he is near multiple interactive objects.
The one-item-at-a-time inventory system creates the most problems; at some points in the game, Manny is carrying a large number of things, and scrolling through them all can be annoying, with the amount of time it takes for Manny to remove each item from his jacket and describe what it is.
There are still several non-diegetic elements left in the game. The conversation system is a notable exception to the immersive interface. When Manny speaks to someone, Grim Fandango presents a rather standard conversation tree interface, with visible options that the player can scroll through and pick from. It's understandable why the developers made this choice.
A diegetic alternative could be created, maybe letting Manny think about various topics in his head and mumble the options to himself, but this would probably be even more awkward than the inventory system... and would make Manny's character much more tongue-tied and socially awkward.
The other major non-diegetic element is the music. Most of Grim Fandango's music is non-diegetic; generally, the wide array of jazzy tunes don't come from an in-game source. This is in keeping with the cinematic feel of the game.
While the music seems to work against the player's suspension of disbelief, it does support the illusion of the game as film. This is an aspect that would have been easy to make diegetic; there are ample opportunities in the world of the game for diegetic music. However, the developers' choice to make the music non-diegetic doesn't weaken the game.
The Fourth Wall
Diegesis is fundamentally a method of bringing the player closer to the game. Every non-diegetic element, whether it's a mouse cursor or a soundtrack, serves to reinforce the "fourth wall" between the player and the game world.
By removing non-diegetic elements, the developer can make it easier for the player to lose herself in the game via immersion. That isn't to say that immersion isn't possible in a heavily non-diegetic game, but all other things being equal, a diegetic game will be more immersive.
There's an important caveat, though. If an element of the gameplay experience is made diegetic at the cost of usability, the player is pulled out of the experience again. Consider Manny's coat-based inventory; using this system is actually more difficult than it would be for Manny to actually pull something out of his pocket.
In this case, immersion would probably be restored by using an easier but less diegetic inventory system. This would undermine Grim Fandango's goal of creating a cinematic experience, but it would make the game less frustrating and easier to use.
Grim Fandango is one of the most well-crafted video games of all time, and it has a lot to teach us about how video games can and should be made. Its use of diegesis is probably the way in which the game is most unique among games.
Diegesis is something that all developers should consider in the course of making a game: when is it better for an element of the game to be diegetic, and when is it best to make it separate from the game world? By considering this, developers can ensure that their game strikes the best balance between immersion and usability.
[Gregory Weir is a writer, game developer, and software programmer. He maintains Ludus Novus, a podcast and accompanying blog dedicated to the art of interaction. He can be reached at Gregory.Weir@gmail.com.]