Anathema is a role-playing game (with some strategic elements). Unlike most RPGs it focuses on cooperative narration, wherein both the GM and the players help move the story forward. This is a very practical way of doing things in a PbP game since it means we can tell more story with less posts.
For those of you unfamiliar with the concept, here are some guidelines:
A) YOUR actions should move the story along - it's not the sole responsibility of the GM.
What we are attempting to do is to drive the story forward; imagine for a moment the camera of the film of the game is focusing on your PC and NPC - this is your opportunity to move the plot and/or action onward and create more hooks and more fun for the audience. Keep it flowing, moving and try to offer options for progress within your post.
Think of the GM as the one who provides the framework for the scenes. He'll also help add content, but he can't provide it all. Without your help scenes will be hollow and unsatisfying.
B) Do not assume too much (but don't assume too little either).
While the GM and the players would like flowing, exciting stories, please remember your character is not a one man army. If you are in combat write blows that hit you in, that scratch and scrape, which later can prove to be more deadly. Allow the GM and the other writers "wiggle room" to tailor the story for a broader audience. You might be a hero, but so are (probably) the people arrayed against you, even if they are not players. There are also clear boundaries not to cross; do not write in significant actions (or reactions) for other PC's or major NPC's and do not make your character a super-hero.
That said it's not cooperative narration if you don't dare to move the story forward. You ARE allowed to write actions on behalf of both other PC and NPCs, but don't do it in such a way as to take away the freedoms of the other players or quickly resolve challenges presented by the GM. Getting it right might sound a little overwhelming at first, but once you get the hang of it it's no trouble at all.
C) Keep your actions open and not closed.
When writing your narrative it is best to consider that the action you are attempting may fail so include the main concept of what it is you are doing in a manner that is clear and direct but unresolved. If you attempting to chase someone down, then say that is what you are trying to do but couch it in IC terms and leave it open to judgment.
I.e. the Champion called "Bob the Nob" is in combat with a big bad Loyalist Astartes which is the "end of level boss" and has been the entire point of the adventure. He wishes to use his new daemonsword to strike. he should write "Bob the Nob ducks under the swinging lightning claws of the deluded marine and swings the sword with all his force, aiming for the rough mane of fur draped across the Space Wolf's shoulders." He should not write "Bob the Nob ducks under the swinging lightning claws and swings the sword with all his force, severing the loyalist's head from its shoulder."
In both cases you're helping to move the story forward, but by deciding the outcome of your own actions (and the failure of the marine to dodge) you've taken too much liberty when it comes to the challenge - and you've robbed the other players and the GM of the opportunity to participate and contribute.
D) Say "yes, and..."
When building on the shared story, accept others' contributions and build on them. Almost never annul or veto anything. If someone describes an action where your character is thrown on the ground, do not say "no, he can't do that, he would not fall". Instead describe how you roll with the fall and swiftly regain your feet, or how you from you new position sweep at his legs and pull him down as well.
Of course, if something does violate your limits for your character, your comfort zone, then saying "I'm not ok with this" is fine and should, IMO, be respected. Just make sure your limits aren't "if my character appears less than perfect". Also, sometimes the GM or the rule-system does things we do not like, then it is almost always better to just roll with it.
E) Pass the ball
Try to intentionally make your descriptions incomplete, so others can use what you left unfinished to build their contribution. For example, in a duel I might write that "The Inquisitor makes a feint at you, but overextends and has left her side clearly exposed..." the intention is clearly that my the player of my character's opponent can build on this. This can be applied to many other situations, like warfare and conversations. Leave some blanks for others to fill.
F) Unimportant bystanders and participants are good tools for dramatic action
If you are describing someone fighting a unit of soldiers, then killing a few soldiers is a good way to provide some action and make your character look cool. Especially in action scenes, there will often be a primary opponent (the villain) and his minions. Kill a few of them, hell have a few of them jump out (there is always another ninja behind the door), just do not describe your character sending all of his minions running, as that changes the situation too much. The same can be applied in other situations - like in a court. Have someone shout from the sidelines, only to be shut down by a few well-placed words.
G) When in doubt, take a hit
If you're in doubt as to what to write for your character, especially in action scenes, the easiest trick is to describe your character taking a minor injury or some kind of setback. Describe how he stumbles and falls, then describe how he gets up again or turns it to an advantage. In almost all action movies the main character always takes a terrible beating (Die Hard I, anyone?), then gets up and does the job. It is a good way to raise tension and to make characters look tough - or to make them look human and mortal, depending on the situation. Again, it can be used outside of action scenes - having your character fume in anger, to look at a loss, etc.
H) Be careful with headspace
Describing why your character does something or what he is thinking is a cool way to add something to the narrative. I like it myself. However, it should always be clear what part of your description is visible to others - that way the other players know what they can have their characters act on. Use a different font or something for "thought bubbles", make it clear. It should also be used in moderation, the focus should be on what those who are together with or close to your character can perceive.
