Alright. So!
After playing through Dragon Quest XI for more than 90 hours (still playing it, by the way, actually). I've had an idea come to me that I'm surprised hasn't before. Besides reading manga and watching anime frequently, I also play video games on a regular basis. Something like averaging 45 hours every week or so, unless I use most or a portion of that time for my writing because I'm feeling particularly inspired.
While I do dabble in games like The Sims, Harvest Moon, Yakuza, and visual novels, the vast majority of the games I play fall under the tag of JRPGs (Japanese Role-Playing Games). One of the most common devices in these types of games is the use of "Silent Protagonists". Above-mentioned Dragon Quest XI uses this, in that the main character never has any spoken lines, just the occasional option to respond with a simple few responses prompt which doesn't actually change more than maybe a line or two of dialogue and every other time he will either nod in agreement with whatever is being said or asked, or make small noises of discomfort, pain, or happiness.
While I love characters and personality, this is such a common thing in JRPGs, that it's hard to not find myself playing at least 12 games a year with these sort of set-ups. Take the Persona and Shin Megami Tensei series that I happen to be a huge fan of.
But on the other hand, there are just as many games like the Tales of series, Final Fantasy, and Legend of Heroes (Trails of Cold Steel for a more recent example) that have main characters with personality, vast worlds, and a cast that can be either just as distinct and unique as normal people, or basic stereotypes that never get fleshed out past the bare-minimum.
My point is, I've decided to explore just what exactly happens to these "Silent Protagonists" and the whole "inside a game" genre of the writing industry that exists exactly because of the large amount of videos games and how popular they are out there.
My main problem is I haven't personally read a lot of stories that do this well. (I have a difficult relationship with the Sword Art Online series as a whole, mostly the mess that is the anime, so I won't count that). While I can easily envision how to make a game work on a writing level in my mind, its a lot different when you try to put it on paper. How do I show accurately that this is a reality that has been transformed into a game?
I can envision how the UI (User Interface) and the menus will look. I can even sit down and try to dissect the battle system and I've even figured out the way "multiple" endings will be decided and visibly tracked by the game's system to the player. I can get things like this down because of the amount of games I've played myself and the things I've seen work well and just end up being a mess. (Though I will admit I'm still torn about the way the Class/Job/Role system I have envisioned will end up working out because I quite liked the system from Final Fantasy X-2 and would like to do something similar here, but we'll see.) But I don't know how this should/can be easily translated into written form as video games are such a visual piece of media.
If anyone knows of any novel series that do this well (or comic if they are explained in an easy to understand manner), please do share! If it's something you've read on here or somewhere else or even something you yourself have written. I would love to check it out and get a feel for how this style of media is conveyed well.
...Also, I'm very sorry for how long this mess of thoughts ended up being. I just felt it might be good to give some explination for anyone who isn't quite as familar with the general JRPG field. I would like to thank any poor soul who might respond to this in advanced. 
Thank you! 