Writing about the then nascent movement of 'The New Brutalism' in 1955, Reyner Banham gave (in between jabs at architectural marxists that in his account ran wild in London architectural circles at the time) three defining points to the style by using Hunstanton School, designed by Alison and Peter Smithson and then regarded as the first Brutalist building of the movement, as a point of reference.
The first two points really flow into each other. Banham very broadly means that the form of the building should follow its function. When you see the building, it should appear as a coherent whole that lets you easily grasp its function. Its also very funny that he goes on to say that this ought to be the commonplace default and that a movement has emerged having 'what if architecture was useful to people' as a defining trait is a damning indictment of the state of architecture generally.
'The fact that this form-giving obligation has been so far forgotten that a great deal of good building can be spoken of as if it were architecture, is a mark of a seriously decayed condition in English architectural standards.'
Valuation of Materials ‘as found.’ means that if a building is made of brick, it should look like its made of brick. Ditto with any other construction materials. This can also be extended to the functionality of the building. 'Water and electricity do not come out of unexplained holes in the wall, but are delivered to the point of use by visible pipes and manifest conduits. One can see what Hunstanton is made of, and how it works, and there is not another thing to see except the play of spaces.'. Another term I've seen to express this idea is 'architectural honesty'.
Really this can be summed up as architecture about people, that pays mind to how people actually move through and use spaces in their day to day lives and values that utility. More specifically it also emerged in post-war Britain and gained a strong association with social housing of the period. (Did you know that at its peak nearly a third of the population lived in some form of social housing!)
If we try and apply this to digital video game spaces though, especially in a game like Quake, I think a few problems appear.
Mainly is that Quake spaces typically do not have a function oriented towards anyone but the player. Even if a building in Quake might give the impression of a real world space; an office, a lobby, a bedroom, they do not function as those spaces. They exist to facilitate the goals of play the game has laid out, to let the player explore and conquer their labyrinths while gunning down monsters. I am tempted to say that this is still in some sense form following function. A space has been designed with a specific player experience in mind and must conform to those needs, it also usually has its own internal coherency that emerges from shared elements of design. Repeated visual elements of the same style: doors, buttons, windows, stairs, as well as the way it uses its verbs (mainly shooting and jumping), build understanding of the space and do allow a player to grasp its function, at least as it relates to play.
The problem I think is that I am also describing conventional goal oriented game design as a whole. This could easily apply to a host of 3d games in a way that makes it so broad as to be meaningless.
More than that, player oriented functionality also challenges the 'architectural honesty' part too. It works well enough when we're talking about basic materials. Brick is brick, concrete is concrete and so on. They are as they present themselves, aesthetically and functionally. These worlds are in many ways fundamentally dishonest though, all facade with no practical purpose. What do exposed water pipes or electrical wires mean when this is not a world where electricity and water really flow?
I'm not really sure exactly how to resolve this. Perhaps the inherent solipsism of a first person game is just unsuited to carry these values and they would be more at home in some form of city builder or management game.
Fortunately it is for the most part, a bit moot. By and large brutalism (at least in a European and North American context) is widely interpreted in pop culture to be more an aesthetic than any guiding ideological principles. More specifically, it tends towards concrete and uses it to invoke authoritarianism, faceless bureaucracy, cold dystopias. Most of all it aims to make its inhabitants feel small and insignificant. Think the dystopia of Papers Please or Half Life 2, the bureaucratic institution at the heart of control Control , the megastructures of Metal Garden This is the lense through which the main mod was designed and through which most of the mappers interpreted it (Robert Yang's being the main notable exception).