Face-to-face: In-person games have great advantages in speed. It's much faster when you can see and hear players clearly. You can use physical props readily: miniatures, dice, and game boards are easy to use in-person. But there are disadvantages to face-to-face: there's no built-in, automatic record of game play. You have to schedule a time and you can only play with the people who show up. During play, the GM either has to prepare for a variety of different player choices, or limit player choice, or be good at improvising. I find game play less immersive in person: it's hard for a GM to play multiple NPCs at once who are presenting different perspectives or arguing with each other. It's also hard for a player to convincingly play characters who are very unlike the player.
Video or voice-based games: I have little experience with these, and what I do is mostly "this is an inferior version of face-to-face." The only advantage I know of over face-to-face is "you don't have to physically get people in the same room". If there are others, they've eluded me.
Online scheduled games: My own experience with this is mostly on MUCKs, but it's played similarly for me on other text-based chat clients. This style approximates face-to-face in that participants all show up at a scheduled time, all play and respond to each other in real time, and stop playing at the end of the session. The advantages of this style: it's easy and natural for the GM to switch between characters, and participants can easily be characters who are nothing like themselves. The GM still needs to prepare/improvise, but usually has a little more time to think between actions, because play is slower. Disadvantages: play is slower (everything has to be typed). There are "virtual tabletop" tools out there; I don't know if these come close to the ease of setup of real props now, because I haven't tried them in years.
Online unscheduled synchronous games: This is the MUCK style of "you show up when you want to roleplay and play with whoever's there". I have never found this to be a very satisfying model of roleplay, because it's hard to tell a story when you don't know who will be involved in it or for how long. Sometimes this encourages burnout -- people who are hyperinvolved and always on and always playing until they flame out after a few months. But I've known other people who made it work. The main advantage over scheduled is in the name: you don't have to schedule play.
Email or forum-based games: These play fairly similarly in my experience. Participants play by posting to the email group or forum. Play is asynchronous: you send a post to the group and you get responses hours or days later. Email is good for games that are driven by conversation or player actions that don't require die rolls. They are terrible for games with a lot of combat or anything else that requires die-rolling. It's good in that you don't have to schedule a time for it, and bad in that it can result in burnout -- people can't look away from the game for fear it will get away from them.
Discord is an interesting medium for a game because a Discord chat group has a persistent history. MUCKs and many chat clients only show you the activity while you are connected to them. Discord will let you scroll back to the start of the chat, if you want.
Discord can be set up to give notifications, or not, so it's easy to see if a chat is active or to ignore it.
For various reasons, my own preferred play is unscheduled and asynchronous. I am generally okay with responding in a time frame of "several hours" and run into issues when it's "a few minutes".
And I am thinking: how do you structure a story so that it best accommodates my style of play? For example, I know that if I want to play a combat-heavy dungeon stomp, I'm best off doing that face-to-face.
But if I want to have a game where:
* Play is unscheduled and unsynchronous
* Participants are involved at varying levels of commitment: some people respond quickly, some respond slowly
What kind of features built into the story will best enable that?
One thing that I discovered while playing with Bard Bloom was that telepathy among the PCs was extremely useful for keeping a game active. All the players could talk to each other without the GM needing to be involved in the conversation, even if the party was presently split up.
Splitting up the party had advantages in forum/email play that it doesn't have in most other forms of play: it allows the GM to interact with each player on that player's priorities, without them getting trampled over by players who respond more quickly. This requires a pretty active GM. In theory, you could get this same effect in Discord by splitting the party between different chat channels. I'm not sure how well it would work in practice.
Mostly, I am thinking about story features like "telepathy": things you can set up so there's an in-character explanation for something that is useful/needed due to out-of-character reasons. What if there's a story explanation for why characters are more or less active at different point in the story, for OOC reasons? One of my friends used to play a game where the characters all had a curse that sometimes one or more of them would turn into a gemstone, and the other characters would have to protect them. The "curse" took effect if the player was absent that week. This isn't a very compelling storytelling hook by itself, but it's the kind of thing I'm thinking about. What if the game took place on an astral plane, and characters act at different speeds depending on arbitrary factors (that amount OOCly to "how available were various participants?") How do you structure this so that players don't feel like they're disadvantaged if they're not around as much?
Anyway, I am kind of stuck on what kind of stories lend themselves best to the format, and what kind of system. So I wanted to write this out and see what other people thought. :)