Abstraction of Instantial Assets. Their focus on meaning in mechanics notwithstanding, proceduralist games do not reject graphics, sound, text, or even story entirely. But when they do include such things, these games tend to reject verisimilitude in favor of abstraction.
Part of the reason for this is practical, as these games are often created by one or two people. But a more important reason is aesthetic: reducing the player's obsession with decoration underscores the experience of processes, while still allowing image, sound, and text to meaningfully clarify the fiction of the game's theme.
Although one common method for abstraction is two-dimensional rendering (as is the case in Braid, Passage, and The Marriage), not all proceduralist games adopt this perspective; an example of a 3D proceduralist work is Mike Treanor's Reflect, a game about the movement of creatures small and large. Treanor's low-poly 3D rendering style de-emphasizes the visual fidelity in favor of the experience of movement.
When it comes to story, procedural works tend to employ metaphor or vignette instead of narrative. Daniel Benmergui's The Storyteller offers an instructive example: a story is told by means of the causal relationships between different characters, at different times, in accordance with their position on a triptych-like stage.
No matter the level of abstraction, proceduralist works don't mistake higher abstraction with lower production value.
Where image, sound, and text is present, it is carefully selected and incorporated into the system that forms the rest of the game -- the time-reversible background particles in Blow's Braid; the expressive six-pixel eyes in Benmergui's I Wish I Were the Moon); the logarithmically scaled distortion of past and future vision in Rohrer's Passage. Such assets are always tightly coupled to the gameplay itself.
Subjective Representation. Games like Go and Tetris are abstract; if they have any aboutness, it is limited to the experience of the system itself. One can make representational claims about these games (as Janet Murray did of Tetris in Hamlet on the Holodeck), but only in an overtly metaphorical way.
By contrast, games like SimCity and Madden are concrete; they deal very clearly with specific subjects and activities, in this case urban planning and American football.
Proceduralist games sit between these two poles. Their systems characterize some aboutness that is not an accident of genre or convention, but one deliberately selected -- often from personal experience.
At the same time, proceduralist works are not as clear about their representations as are other games. There is an ambiguity of both form and signification in these works.
Another example of the style, Bernard Schulenburg's Where is My Heart demonstrates both of these aspects. The game deals with "the complication of family life" by distributing success among three abstract characters and jumbling an intricate platformer world about the screen.
From the perspective of form, proceduralist artgames tend to combine concrete, identifiable situations with abstract tokens, objects, goals, or actions. Consider, for example, the blocks in Rohrer's Between (previously discussed in this column), which are abstract objects that also play a role in a concept or set of ideas about the gulf separating individuals.
From the perspective of signification, proceduralist works deploy a more poetic and less direct means of expressing the ideas or scenarios their processes represent. Braid poses questions about doubt, forgiveness, time, and regret, offering the player an opportunity to pursue the question, "what if I could go back," in different ways.
However, the answers to these questions are not presented as definitive solutions discovered automatically through mastery of the game's system.
In this sense, proceduralism shares some of the values of Expressionism in art, especially as both relate to the subjective interpretation of emotion.