The Sprawl RPG and Play-By-Post Medium
PtbA games are funny beasts. They depend a lot more on the chemistry between the players, and between the party and the GM, than they do anything else. If you get the right four or five people together, they sing like nothing else does. But if you get one person who's not doing it right, it can sink the whole operation. And that tendency is even stronger in PbP, where you can't just clear up a disagreement in two seconds and move on. Little gripes and conflicts linger for days and days.
Anyway, some specific things I've noticed after failing at PtbA games over and over:
-Players tend to want to end every post with a Move. It makes sense, that's the main way they interact with the system and the world, but the way PtbA games are structured, Moves generate narrative, so if everyone is doing one every post, the actual game just dissolves in a sea of random events.
-When I run PtbA games, I try to set expectations that the game should be something l like 80% freeform, at least at first, until everyone finds their feet. If something actually triggers a Move, fine. But if you don't set that expectation, I find players try to twist their posts into something that will trigger a Move, and that causes even more issues. So that's my first screen: players who don't like freeform, or don't 'get' freeform, tend to have trouble with on-line PtbA. Even combat (especially combat), dice-game players want to do a thing, roll a dice, do a thing, roll a dice, but that's not the way PtbA works.
-Find ways to skip over discussion steps, within reason. This is also part of the freeform thing. If you're fighting some mooks, and they're not threats, then tell me me what you do, tell me how well it works, tell me what happens. You don't need pause after telling me, in freeform, how your Adept ninja-kicked the crap out of a pair of security guards. Just narrate the whole fight for me. Even if the post involves a Move - so long as the result doesn't require an MC Move as a response (which usually means, so long as you rolled over 6), just tell me what happens. Around a table you can just be like "I ninja-kick them" and the MC can be "They're all busted up" and you're like "Did I break his face" and you're like "You totally broke his face, he's crying" and you all cheer and move on, but on PbP each part of that exchange has a 24-hour delay and everything grinds to a halt.
-Expanding on that a little, it's sometimes beneficial to say to a player 'this is the situation, tell me how you handle it.' And let them finish the scene however they like. Sometimes that means their role slides into the MC's a little. That's not how these things usually go and it can be a hard transition. That's my second screen - writing in a co-GM way is very different than writing in a purely PC way, and some people don't like it and can't do it well.
-The combination of these things, above, mean that trust between participants is HUGE. You're letting a PC loose in a game world with very few mechanical constraints on what they can and can't do. Most of what dice tell you in a PtbA game is what happens when you successfully do the thing you were trying to do. So if you're like "I stomp my feet and cause an earthquake that levels Tokyo" the only thing stopping you is a general consensus to not be a jerk. But not everyone has the same definition of what being a jerk entails, or what's reasonable, or part of the general consensus. So when someone does go too far, instead of everyone freaking out and just typing MARY SUE!!!!!11!!1!!!111rofflecopter in bold and flouncing, there can be a gentle correction, maybe a small retcon, and everyone moves on. But even when they work well, those things slow everything down (again, think of a simple that's too far - is it? - it is - what was too far? - that thing you said - I'm sorry - that's cool, just take it back a step - Cool I will - with a 24-hour delay between each part, and with everyone else having a day to voice their opinions about it before a ruling can be made, added to difficulty in effectively communicating tone over text).
-That's why chemistry is so important. And why one bad actor can just wreck an otherwise amazing game. So when I pitch games, I spend a lot of time (too much really) discussing tone and mood and genre conventions and general expectations. And when I get a group, the first thing I do is "Tell me three things that Cyberpunk means to you." so we can make sure we're all playing as much the same game as possible. Is your Cyberpunk about hope? Or hopelessness? Is it about remarkable individuals standing out in an ocean of dystopian conformity? Or are they regular people forced to reckoning with things they're not prepared for? How gritty? How grim? How granular? All these things become much more important when you don't have a robust, simulationist system to smooth over the rough spots (like, in D&D, it does't really matter if your Sword and Sorcery is Conan or Jackie Chan, you have a bonus to hit and a damage dice and that's just it).
-I don't use this one myself, as I'm not on-line often enough for it to be practical, but I've seen MC's use the rule that, whenever anyone's post invites or requires an MC move in response, everyone just stops posting until that Move happens. It's a very, very, very good way to control the narrative flow, but at the price of momentum. And, in my experience, momentum is the second most important factor in a PbP game lasting. But YMMV.
The main benefit of PtbA games on-line is how fluid they are. Combat boring? Just end it. Scene not working? Hard frame a new one. Because the base expectation is that the system is not modelling 'reality' but rather guiding narrative, you have a lot more freedom to move things forward and guide them to interesting places without getting stuck on Tracking rolls or failed Knowledge checks.
And, when it's the right group, being able to download some of your lower-stakes GM duties is absolutely electrifying. But with the wrong group, it's a disaster.