See Angry's original GM Credo post.
Here is my personal GM credo. Like my article on prep, this is about me, not advice for how you should run your game. This is how I run a game. You might have a different credo.
My credo is based on my personal vision of the GM as a facilitator. First, the GM has to sell the game concept to the players. After the players have bought into the campaign and adventure premise, the GM becomes their facilitator.
Notice that rule #1 is very important. It's rule #1 for a reason. If I want to run a particular game, I have to sell it first. I have to be transparent, descriptive, and clear in the pitch. Railroading only happens when the GM forces the players toward an objective they do not share, so if I get everyone to buy into my pitch, then unless I lose sight of my own vision, I'm not likely to railroad the players.
Here are the rules, in short form. They are written as instructions in the imperative tense for my own use as a GM. They tell me to do things.
1. Attain group buy-in to the premise
2. Strengthen the group’s consensus of the game’s shared objectives
3. Listen and respond to the players
4. Create the challenges of the story from the highlighted player-suggested ideas
5. Facilitate inclusion
6. Decide when to use the game rules
7. End scenes that suck
I know what these shorthand instructions mean, but you're not me. Here's some more explanation of each one.
1. Attain group buy-in to the premise
I must attain group buy-in to the premise and objectives (story hooks and artistic objectives like genre, theme and mood) of the campaign and each major chapter (or adventure, scenario, or module) of the campaign. This will be referred to as shared objectives.
2. Strengthen the group’s consensus of the game’s shared objectives
I must promote, maintain, and strengthen the group’s consensus of the game’s shared objectives over the course of the game. I will help the group come to consensus and resolve out-of-character disagreement over how to apply their shared objectives to the problems they encounter in the game. I will promote in-character discussion of how to resolve the problems the PCs encounter in the game, so that the players can explore different ways to resolve them in terms of their characters’ abilities, hooks and personalities. If the group’s shared objectives evolve and change over time, I will have a frank, out-of-character discussion with the players and achieve consensus on the new shared objectives.
3. Listen and respond to the players
I will listen and respond to the players, repeating, asking for elaboration on, and emphasizing the ideas and plans they come up with that best underscore the group’s shared objectives. I will remind the players to propose actions that would take the story in directions that they would enjoy playing, not just what their character would do.
4. Create the challenges of the story from the highlighted player-suggested ideas
I will create the challenges of the story from the highlighted player-suggested ideas. The challenges include the obstacles to achieving the PCs’ plans and the actions of the antagonists. In a way, the players decide who, what, when, where and how, and the shared objectives establish guidelines for me to offer them a reason why. Example: The players decide to go seeking a lost golden dragon egg. I decide that the egg is in a hidden temple in some remote, ancient ruins guarded by evil cultists who are trying to corrupt it. Later, they decide to sneak into the temple. I decide to present stealth challenges and temptations to risk being noticed along the way. Later they decide to banter with the evil high priest with swords drawn, so I should banter back instead of end the banter prematurely by having him try to get the drop on them.
5. Facilitate inclusion
I have a responsibility to, and therefore must facilitate inclusion. I must design situations in the game that allow all the players to participate at the level they want to, to the best of the GM’s ability. Where a conflict arises, such as a lot of players who want a lot of spotlight time, the GM will design situations in the game that equitably balance the players’ desires. I will ask players to step up or step back to include more introverted/shy/anxious players. Another definition of inclusion is awareness of privilege and sensitivities. I will keep the game from wandering into areas that could be awkward or uncomfortable for players. I won't tolerate any form of gatekeeping.
6. Decide when to use the game rules
I will decide when to use the game rules. If the rules of the game produce fair and transparent outcomes, I will use them to add drama to the situation. If the rules bog the situation down (and the situation is not supposed to feel bogged down), I should chuck the rules and allow the players to resolve the situation. Fudging die rolls is OK, as long as it’s not done in secret. I should feel free to announce a die roll result, then explain why I want to fudge it. If the players don’t care, then I can do so. I should also be OK with players objecting to die rolls and asking for the result to be fudged.
7. End scenes that suck
I will end scenes that suck. If a combat or skill scene is dragging; if the players are locked in “analysis paralysis”; if some of the players – myself included – are not having fun, I will end the scene as soon as I realize this and skip as much action as necessary to get to a scene that might be more fun. If some players object, see rule 2, but also see rule 5. If all the players object, see rule 3 and 4. If the system doesn’t allow it, see rule 6. As for which scene to move on to, see rule 4.
Disclaimer: These are living ideas. This is a document that will always be a rough draft. If your credo differs from mine, it doesn't necessarily mean we disagree.