Gming Gamemastering
Getting Ready The Three Commandments of Gamemastering
Overseeing Character Creation
Playing the Game Running a Game
Creating an Adventure

The first step to being a good GM it to understand the very basics of running a game. You need to learn how to walk a fine line between running a dictatorship and total anarchy . The best way to learn it is by doing it, but before tossing you to the sharks, this chapter will start by giving you some advice on how to do the job.

It's Your Show (By Their Whim)Edit

When players and the GM sit down at the table, they enter into a sort of unspoken social contract. The GM runs things, arbitrates rules questions, and creates the world. At the end of any argument, the GM's word is final. If there's ever indecision or uncertainty at the table, it's up to the GM to resolve it. In d20 Advanced, the GM's job in this respect is even more essential. As a toolbox system, d20A relies heavily on a GM making smart judgment calls based on descriptors, how an action will be performed, or just a general idea about how a character usually acts.

Learning to Say "No"Edit

Starting with character creation and continuing on throughout gameplay itself, a good GM needs to know how to say "no". As a toolbox game, where the rules are meant to represent concepts and ideas from countless genres, you as the GM must be prepared to tell someone when an idea they have threatens to disrupt the game.

When it comes to character creation, understand that there are many character concepts which are completely legal according to the rules, but which have absolutely no place at a sane group's table. You need to learn how to inspect a character sheet and decide whether or not it will be problematic for you to run that character or if that character might not fit well with the other characters in the group. You don't want someone to bring a super-cyborg gun-bunny to a game set in an ancient, magical world of swords and sorcery just like you don't want someone using a potentially overpowered character at the table either. More on this to follow under Overseeing Character Creation.

Further, a good GM needs to know how to tell somebody that a certain action in game is not an acceptable option. Sometimes stunting a particular FX just isn't appropriate for the game (such as a fire-mage in a fantasy game trying to create nuclear reaction by splitting the trace amounts of helium with a flame spell).

As a rule of thumb, if a player is trying to sell you a Rube Goldberg Machine explanation for an idea, it's probably time to say "no". Rube Goldberg was a cartoonist who designed comically convoluted machines for handling various common household tasks, often involving countless inefficient steps arranged like a bizarre set of dominoes. Players sometimes like to use the descriptors on their FX with similar levels of convoluted mental gymnastics to justify their actions. The rule of thumb to keep in mind here is to question any idea which requires more than three "and then I can..."s, or any idea which requires knowledge which really isn't possible for the character to have (such as the infamous fantasy wizard "accidentally" inventing gunpowder by "accidentally" knocking all the ingredients together in the correct ratios and then "accidentally" testing it). But be careful: you don't want to penalize players for smart play. Learn to distinguish between good tactics and Rube Goldberg explanations, and you'll be well on your way to being a great GM.

The Player's Eye vs. the GM's EyeEdit

One of the most important things for the GM to remember is that almost by default, the GM has a very different view of the game than the players do. Players are generally fixed in their view to their own characters, or at best, the group of characters itself. The GM, on the other hand, holds more of an "overhead" view of the entire situation, remaining perfectly aware of things hidden to the players and their characters.

Sometimes, especially if you haven't been a player in a long time, it's easy to forget how limited the players' point of view can be. What's obvious to the GM could be all but impossible for the players to even perceive. Try to get a feel for what the minimum threshold your players need to perceive something. Sometimes players are exceptionally sharp and will put things together even more quickly than you do. Other times, the clues and hints you provide just don't seem to be enough. When faced with this, you need to try to blind yourself to your own perspective and look at it from the players' point of view. Can they reasonably draw the conclusions you expect them to from the hints you've given them? Could you spot the pattern given the same information that they have?

The other important point to remember is that when it comes to gaming, everyone wants a chance to shine. If they feel like their characters aren't getting the spotlight enough, the players are likely to be unhappy. As the GM, you have to remember that from the players' point of view, their characters are their favorite parts of the game. Everyone remembers the cool moments when their characters stole the scene and had everyone cheering. Players want a chance to show off, to be the heroes of the story. A good GM needs to know how to give everyone a chance to enjoy the spotlight, how to create exciting moments for the characters to really shine.

Depth is an IllusionEdit

As far as your players are concerned, all that exists in the world you're showing them is what is in front of their eyes. This is related to the above point about player viewpoint versus GM viewpoint. For example, if you design a dozen cities for your group to explore, but they only ever adventure in one of them, then the other eleven might as well not exist.

Just like a movie set or a theater stage, the background of your world need only be realistic and detailed from the point of view of the audience (the characters). If the players only ever see one side of a four-sided building, you could really care less about detailing the other three sides (only so long as your players think that the other three sides are just as well detailed as the first one). The lesson is not to spend time detailing something which may well never come up.

Similarly, you need to be able to think on your feet and be able to quickly fill in the gaps when your players start peeking around the corners into areas you hadn't detailed. Learn to get a feel for what your players consider important, so you know where to focus your attention in designing your adventures. Once you get the game rolling, learn to show the players enough that they believe their characters are adventuring in a fully fleshed-out, dynamic world, and your game will be better for it.

The Social ContractEdit

As described above, players and the gamemaster enter into an agreement when they sit down to game.

The PlayersEdit

The players come to the game with their characters and their characters only. They agree to come up with interesting and balanced characters to bring to the game. They agree to acquiesce to the GM's rulings during the game, and agree to wait until after the game to discuss rules disagreements. The players are also agreeing to give up control over aspects of the world beyond their characters and granting that control to the GM in the interest of creating an adventure. However, it is understood that the players reserve the right to remove a GM who is unsuccessful in upholding his or her end of the contract.

The GamemasterEdit

By virtue of his or her duties, the GM holds proportionally more power in-game than the players do, but the GM agrees not to use this power unfairly against the players' characters. Further, the GM agrees to provide for the players an exciting and appropriate adventure for their characters. The GM is entitled to make rules decisions and use GM Fiat when necessary to make the game more fun. The GM also agrees that if s/he is unable to provide the game that the players with a good game, that s/he step down and turn over the reins to someone else. The GM's power only comes from this agreement with the players.

Use the Rules, Don't Let Them Use YouEdit

The rules for d20A exist to provide a common ground for the players and the GM, a sort of skeleton for how the shared imaginary space which the characters and NPCs inhabit will behave. To a certain extent, the world will always behave in certain ways. Objects always fall downwards. Fire is always hot. Injury always affects the body in certain ways.

For a roleplaying game, the rules exist to provide two things:

  1. A means with which to create different types of characters with varied capabilities
  2. A means by which those characters can interact with the world around them by resolving challenges (both from the world itself and from the people and objects within that world)

Beyond that, everything else is the responsibility of the players and the GM. The rules exist to facilitate creating the adventure, and they should never inhibit it. And no matter how well-designed a gaming system is, it can still cause problems and confusion. As the GM, it's your responsibility to know when to use the rules, and when to use your own judgment.


The rules exist as guidelines to speed play. They're an aid, not a straight-jacket. In general, the rules are meant to follow common sense and allow for quick arbitration. If a player wants to resolve a task, it usually isn't too hard to decide which skill the player will need to roll, or what feat or FX the character needs.

However, even if a specific use of a skill or FX isn't described in the rules, it's generally not a problem to decide that this particular application is acceptable. For example, the rules don't specifically state that you can use the Technology skill to recover data from a damaged DVD, but according to common sense, it's quite applicable.

The trick is to use the existing framework to guide your decision-making. To recover the data off that damaged DVD, you might tell the player to roll a number of four-sided dice equal to her ranks in the Technology skill, and count up the number of 4s she rolled, and that's how you'll determine success or failure.

The problem is that the rules already provide a good framework for determining success or failure: roll a d20 and compare it to the DC for the task. The Technology skill even provides a more precise framework for determining the DC, based on what you want to do and how the system is designed.

As they are written, the rules serve not only to answer questions directly, but also indirectly by providing a uniform set of guidelines for resolving questions.

In general, you can use these guidelines to decide how to resolve a given action in-game:

  • If the task is mundane, or at the very least, not-supernatural, and could conceivably be accomplished by a trained individual in the real world, then it requires a skill check. Tasks which are dependent on your physical capabilities should use a Strength, Dexterity, or Constitution skill; those which are more mental should use Intelligence, Awareness, or Charisma.
  • If the task is directly dependent on the strength of supernatural abilities, it requires an FX check. (Note that you may use Focus if you choose to represent skill and finesse with FX).
  • If the task is an extended contest between two or more competing parties (such as a chase or an interrogation), then this is a dramatic interaction, and will be resolved through a series of opposed checks. Use this option especially when the task is a point of special interest in the adventure and requires additional focus.


There are players out there who are going to want to play things right by the book, and who are uncomfortable with judgment calls and deviating from the rules as written. They prefer it when the game sticks to the rules they already know and are familiar with.

In spite of the less-than-flattering name they are often branded with ("ruleslawyers"), these types of players can be a very good presence at the game table. They often have an excellent understanding of how the rules work, or at least are very quick at locating relevant rules in the book. Learn to use these sorts of players as a resource at the table to quickly and efficiently find rules you don't know off-hand, and let the player know that you appreciate his or her help.

However, ruleslawyers can be disruptive to the game when they become argumentative and unwilling to accept your judgment as GM. The best way to overcome this is by developing trust with your players. Try to roll dice in the open along with the players (since you need to use GM Fiat to re-roll dice just as the players need to use Hero Dice). Try to discuss with your players (after the game, if they wish) how different NPCs you created were built, and how their abilities works. Also try to explain your reasoning for your judgment calls, especially in light of the other rules of the game. Do this after the game, or at least after the action during down-time. You're trying to establish with your players that you are a fair GM who is not looking to take advantage of the power the rules give you. This will go a long way towards easing the concerns of regular players and ruleslawyers alike, making them more comfortable with accepting your judgment calls.

Arbitrating, Not RulingEdit

The GM is a referee and a judge, not a despot. As GM, you have a lot of power which is very easy to abuse. It's very easy to get into a "me versus them" mindset, which is a no-win situation. Within the context of the game itself, the GM is just infinitely more powerful than the players are, since you can simply create and introduce unbeatable foes and crush the players. That, however, can wreck a gaming group and drive the members apart.

As the GM, it's your job to be the impartial, objective arbitrator of the rules, not the monarch passing judgment by whim. Your goal in all rules discussions is to be fair and to keep the game fun and exciting. That means that while you ideally want to keep rules discussions short (and preferably separate from actual game-time itself), you also don't want your players to think that their own input is inconsequential.

But keep in mind that rules by committee are, in general, a bad idea. A good way to handle it is to ask your players when you're making a rules decision if they're okay with it. If most of the players are, you'll not only know their opinion on the matter and have backing from them with your decision, but it also shows that you value their opinions and want them to continue helping you.

That's not to say that there aren't times when being heavy-handed is necessary. Sometimes, for the sake of moving the game along, you need to fudge the rules with GM Fiat. In these situations, you do what you need to do, but be sure to hand the players Hero Dice for their troubles.

"Arbitration" Doesn't Mean "Arbitrary"Edit

The rules are meant to be helpful guidelines, so discarding them whole-hog can lead to problems as well. If you rip the metaphorical rug out from under your players, leaving them stranded and blind as to how the world around them works. In such a situation, the game becomes one of "GM-May-I?" where the rules are inconsequential, and only the GM's whim matters. Rather than using dice to resolve a situation, the player essentially has to ask the GM's permission to resolve it. While some groups enjoy this style of gameplay, it's popularity isn't great, and for many players, it's frustrating for the GM to break the social contract by rendering their character's abilities inconsequential. Ideally, you don't want your game to devolve into "GM-May-I?", but you also don't want the rules to become detrimental to your game either. You have to find the balance that works best for you and your group.

It's All Fun and Games (Or It's a Waste of Time)Edit

The most important thing to remember: d20 Advanced is a game, and it should be fun for everyone involved. Keep this in mind any time you're considering a rules discussion. If a rule is giving your group headaches, or is taking too much time, or is just making the game less fun, then you as the GM have an important role to play. It's your job to take that rule, toss it to the curb, and figure out a rule that works better for your group and your game.

Watching the ClockEdit

Set a mental time-limit for yourself if a rules-discussion gets started at your table and threaten to slow the game down. Learn what sort of tolerance your group has for delays like this and be sure to step in and keep the game moving when it's necessary. When it doubt, use the guidelines described above to come up with a quick way to resolve the issue.

On the other hand, if your group is laughing and enjoying themselves because one of your players just cracked a hilarious one-liner, or everyone wants to take a break to watch a favorite television show, you need to know when to sit back and let the game come second. If your players are having a good time, then you're doing your job right. There's a time and a place to cut down on frivolous chatter, and you need to learn what it is to keep the game moving. But you also need to know when it's time to join in the belly-laughter with the rest of the group because, hey, that was pretty funny.

When to Pass the TorchEdit

A roleplaying game is still a game, and if you or your players aren't having fun, then you need to reconsider your approach to GMing. Reassess how you run the game. Ask the players for feedback, and whether or not they'd change anything about how the game plays. It's not an open call to hand out goodies to their characters, but rather a chance to get honest feedback and opinions on how you can make the game better.

You also need to learn how to sit back and let the players do their thing. As the GM, you might be in charge of the world around them, but the players still have control over their characters. When they're enjoying some down-time chatting with one another, or when they're planning out their upcoming attack, you need to know when to sit back and let them do their job without you. If they need some help or want to talk to an NPC, they'll let you know.

And the last thing to keep in mind: no matter how hard you try, sometimes you're just not going to be able to run a good game. It might just be a bad night, or the game might simply have run its course, and it's time to close up shop, make way for something new. Be willing to let other members of the group give GMing a go. Sometimes, switching things up and trying a new game is just what you need. Some time as a player might give you the opportunity to get some perspective on how you run games (plus it's a nice way to recharge your batteries and avoid GM burn-out). Don't take it as an insult if the players suggest a change of pace. It might just be what you need.