*scribbles notes* Splendid guide. *more scribbling*
I've been actively avoiding using Architect to run plotlines, because I knew that there would be problems and processes worth putting in place to help smooth the ride, but I couldn't think what they were in advance - having witnessed it firsthand last night, I got to see the potential problems and pitfalls (like in-mission clues not being obvious to all players, for example), and figure out ways to adjust play-style to accommodate them.
I wanted to get my thoughts down as quickly as possible, while it was fresh in my mind. All in all it went very smoothly (the clue problem was identified in the very first mission, after defeating the first spawn of enemies - but I certainly hadn't thought about it before that!), which was a testament to the players involved and the dedication of the plot-master. I'll also admit that 20 years of GMing experience in tabletop games helped me a lot, too, particularly with things like setting up the scene. At times it felt like I was taking a lot of control away from the plot-master, but I found that once everyone was in-mission and playing, everyone just lapsed into character, and things progressed pretty much as they always do with IC mishing.
I think it's safe to say that my first IC plotline story arc will be making its way onto the architect server soon™!
The wisdom of Shadowe: Ghostraptor: The Shadowe is wise ...; FFM: Shadowe is no longer wise.
; Techbot_Alpha: Also, what Shadowe said. It seems he is still somewhat wise 
; Bull Throttle: Shadowe was unwise in this instance...; Rock_Powerfist: in this instance Shadowe is wise.; Techbot_Alpha: Shadowe is very wise *nods*; Zortel: *Quotable line about Shadowe being wise goes here.*
This is something of the nature of a guide to RP plot-masters on how to use the wonderful tools given to us with Mission Architect to play out missions for people IC.
Right, where to start...
What is plot-mastering?
Plot-mastering is a bit like Game Mastering in tabletop RPGs, but with a little less control over the environment, and the plot-master (using as standard the male pronoun for ease) will also take the part of one of the player characters involved in the plot - quite often the central character.
Why be a plot-master?
Being a plot-master lets you create stories around your own character, the events that shape their lives, and allows other people to get involved in shaping those events, ultimately creating that wonderful thing we call Roleplaying. It's possible to RP a character without ever running a plot, but sooner or later you'll probably want other people to get involved in some event or conflict that directly affects your character - if this happens, you're a plot-master. It's a chance for the events you create to take centre stage, and for other people to feel involved in the shared world.
What a plot-master isn't.
The plot-master is not God. The plot master cannot tell other players what to do - that's God-modding, and is the cardinal sin of shared-world RP.
Why use Architect?
The tools given to us with Mission Architect enable us to create an infinite variety of missions, with an infinite variety of enemies, scalable to any level. We can place clues, dialogue, create certain events and generally do almost anything. And fighting mobs PvE beats in-game text-description combat every time in my book.
So, how do I create a plotline using Mission Architect, then?
Sorry, this is not a guide on how to do that - I assume you already have a storyline and a series of missions that make up the plot, with the clues, enemy mobs, custom bad guys and so forth that you want. This is a guide on how to actually run your plot using the tools that exist, and how to make things in-mission as smooth as possible. The last thing a plot-master needs to be doing in the middle of an IC mission is stopping the flow of action. By that stage it should all be about the RP.
So... this is a bit of a pointless guide, then?
No! Until I took part in a plot that used MA, I didn't know what was good and what was bad about doing so. I did my first one last night. Not as a plot master, but as the team leader for a group running the arc. That was a piece of insight I hadn't had before, and it was invaluable. Read on...
Part One: Setting up
The characters will be running between one and five missions together (assuming you run a single arc), IC. They will usually need a reason to get together. The normal game assumes that you get missions from your contacts, but in RP there are effectively an infinite number of reasons to get together. The important thing to note here is that this can and should happen before the arc is even selected from the Architect system. The characters should all be together in one place at the same time, and be ready to do whatever it is that needs doing. The needs of the plotline may change this, but that's the basic rule of thumb - be together and have a reason to be together.
One of the participating characters should act as Team Leader - and it should not be the plot-master. The plot-master has other things to worry about, including acting as any (usually non-combat) NPCs in the plotline, and the team leader has other responsibilities.
So, the team needs to consist of
1) Team Leader
2) Plot-master
3) Everyone else taking part.
The biggest downside to this is that the team is limited to 8 people, and you may find that you have more people interested in doing the plot missions than this. I'm afraid you're stuck, and need to find an alternative method of dealing with it.
Part Two: Mission Introduction
You have a team, you have a mission arc, you're all set to roll... and everyone wants to ask more questions. Oops. The limited size of the text available for the mission contact means that you will never be able to fit everything in that you want. My best suggestion here is that the plot-master take on the role of the contact before everyone enters the mission - and in fact whenever the party is outside the missions, the plot-master must be prepared to switch NPC roles. For this reason, it might not be a bad idea to have a Generic contact with the basic mission details set up, so that the plot-master can handle additional RP as required, and so that the plot-master can fudge not returning to the contact after any particular mission, if it's not necessary - the real game includes follow-on missions, but Architect requires talking to the contact every single time. Plots need that flexibility, so it helps to build it into your planning for the plot.
Part Three: In the missions
You should have put clues, dialogue, appropriate descriptions, and, well, everything into the missions when you made the arc, so the plot-master's job inside the missions is really to be just another character. This is actually where the team leader takes on the most important role. I suggest using Team chat as an OOC channel, with Local for conversations and Broadcast (or SG, or a private chat channel) for Comms chatter. The team leader needs to inform everyone when a clue is found, and signalling it on Team will alert everyone to the need to check the current mission's clues. It's then up to the individual players if they bother to read them or not.
Part Four: Between missions
There should be a chance for IC chatter, bringing characters up to date on what happened, and general social interaction. The plot-master can use this time to act as the Contact again, or to let everyone know what else they discover from the clues they found.
Part Five: The aftermath
Once everything's finished, and everyone's saved the day or whatever the objective was, it's time for a cooldown chat, and everyone can go off to do whatever it is that they do after a successful job. The plot-master's job is done... unless the clues lead to another arc you have prepared, ready to run another time.
The wisdom of Shadowe: Ghostraptor: The Shadowe is wise ...; FFM: Shadowe is no longer wise.