The Core Mechanic - LunarNeil/Call-of-Cthulhu-Campaign GitHub Wiki
In a game of Realms of Mythos and Madness several players each take control of an Investigator, special player characters that run, fight and sleuth their way through a terrifying mystery set forth by one friend who plays the Moderator, a kind of game referee who also gets to run the story and play the parts of all monsters and insane cultists that oppose the Investigators.
The core mechanic of Realms campaign, which is to say the most important rule for running the game, is something called Dramatic Arbitration. This is just a fancy way of saying that when there's something you want to do or something at stake in the game, you should handle the question of "what happens next?" it in a dramatic and exciting fashion, rather than by using dice.
This is normally done by telling what your Investigator does in a way that fits the tone of the scene, and meets with the Moderator's approval. You can pretend to be your Investigator and say things like "I open the door carefully..." or be a narrator to your actions, either way is fine. Have fun with it and pretend you're telling a story, because that's what you are!
There are other ways to add drama to the game table too. Whenever something can be solved by doing an interesting challenge at the table, like playing cards rather than rolling a card playing skill check, the Moderator should give the players the option... assuming it is safe to do and the materials are available!
The only rule of Dramatic Arbitration is that the Moderator has final authority on what happens, no matter what anything else says. This means that the Moderator has the right to ignore the rulebook, disregard scenario materials, or override the objections of the players. This should be done in the spirit of fairness and genre authenticity, keeping the game consistent as well as enjoyable.
The Fair Play Rule
The Fair Play rule states that the Moderator should not infringe upon the rights of players to have real consequences for success and failure.
The most common usage for this is to remind the Moderator not to step in on behalf of the Investigators when a situation turns against them. When the players feel that they no longer are being allowed to fail, or that the Moderator is softening situations for their benefit, the horror and tension that the campaign depends upon is lost. It also reminds the Moderator not to punish an Investigator for success when it leads to a situation or plot development that the Moderator finds inconvenient. Fair is fair!
This rule ensures the Realms of Mythos and Madness remains a game that can be won or lost according to player skill and not the whims of the referee. Players must have the latitude to both succeed and fail, because the option to do one without the other renders any outcome meaningless.
Hand-Waving
Handwaving is the term applied to acts of narrative convenience, and refers to the way the Moderator can ignore trivial concerns for the sake of expediency. Whenever a question is less important than the time it will take to determine the right answer, just use the more interesting answer.
The Focus Bonus
The Focus Bonus is an in-character benefit given to the Investigators of players who are helping to create a positive atmosphere at the table. This is not a way to play favorites or make players use strange gestures to denote when they are in or out of character, but it allows the Moderator to discourage distracting behavior without having to "get serious" and punish the players. The rules for the Focus Bonus state:
In any situations where attentiveness or focus are a deciding factor, an Investigator receives greater leniency when their actions are accompanied by descriptions, in-character party chatter, and exclamations of surprise, horror, and excitement at dramatically appropriate moments.
In the simplest terms, this means that if describe what you're doing, talk to your buddies as if you were your Investigator, and keep your ears open for any small cues from the Moderator, your Investigators will get favorable treatment throughout the game. Investigators are less likely to be ambushed, or to fail a task under pressure, when the players are keeping their heads in the game.
This is one of the few ways that the Moderator can intervene on behalf of the players without breaking the Fair Play rule, and helps the players to keep themselves immersed in the world of the game, which makes everyone have a lot more fun.