I've been thinking about aphantasia a lot, because I regularly GM (game master) tabletop roleplaying games. I often tell players at my table to start with a mental image and then I'll help them use the rules to construct whatever makes narrative sense. "Let your vision guide the rules, don't let the rules constrain what you think your character can and can't do." I've tried to figure out what it would mean for my GMing style if I ever had a player with aphantasia.
One thing which I think is often ignored when this topic is discussed is that even for people with vivid mental imagery, many cognitive processes still take place without relying on that faculty. I can remember my birthday without visualizing a calendar; when I want to remember my birthday, the numbers just pop into my mind seemingly from nowhere.
Based on the research in this paper, I could see a few ways to make a ttrpg work for aphantasics: allow time for them to do a quick sketch to figure out what they want, rather than (or in addition to) suggesting mental imagery; avoid metaphors and similes and instead focus on what would be observable facts in a scene; and be prepared to offer more artwork and diagrams from my side to get across my points, instead of relying purely on theatre-of-the-mind.
I'm also a TRPG player and GM, and I have total aphantasia. I can't possibly speak for all aphantasics, but I wouldn't want you to make most of those accommodations for me if I were a player at your table.
Metaphors and analogies are very useful for me, because they provide archetypes of mental models for my understanding of the world (in this case fictional). There's nothing inherently visual in them or difficult for me.
I love to see artwork, and maps certainly help understand the geography of a scene, but I'm not sure that has much to do with aphantasia. If the GM's verbal description is good, I actually prefer not seeing pictures, so that I can fill in what I can with my own imagination.
Maybe the biggest thing that aphantasia does in this context is give me a strong filter against "useless" details. If you describe a monster with knife-like jaws, or a woman with pink bubblegum hair, that's interesting because they are potentially useful "action hooks", i.e. knowing those might influence my decisions, be it tactics or conversation prompts. On the other hand, if you describe all the random colored spots on the monster's back or tell me that the woman's hair is blond with curls "like overcooked macaroni" or whatever, those are not going to mean anything to me, and they're going to bore me.
One thing which I think is often ignored when this topic is discussed is that even for people with vivid mental imagery, many cognitive processes still take place without relying on that faculty. I can remember my birthday without visualizing a calendar; when I want to remember my birthday, the numbers just pop into my mind seemingly from nowhere.
Based on the research in this paper, I could see a few ways to make a ttrpg work for aphantasics: allow time for them to do a quick sketch to figure out what they want, rather than (or in addition to) suggesting mental imagery; avoid metaphors and similes and instead focus on what would be observable facts in a scene; and be prepared to offer more artwork and diagrams from my side to get across my points, instead of relying purely on theatre-of-the-mind.