Most Role-Playing Games (RPGs) require one player to take on the role of Game Master (GM). There are some exceptions, mostly in the “Story Game” sub-genre of the hobby, but even those often have players take on GM-like roles during some parts of the game. If you think of an RPG as a movie where the game characters are the stars and the players are the actors, that means the GM is the rest of the cast and crew. Her job is to write the rough outline of the script, build the sets, play the supporting characters and extras, and do dozens of other things to make sure everything comes together to create something the audience (in this case, the players) will enjoy.

Game Mastering is much more challenging than just playing a character in an RPG. Most players can forget about the game when they’re not sitting around the table, but the GM will have to spend time and creative energy between games to prepare for the next session. During the game itself, nearly everything that happens requires the GM’s attention, if not her direct input and participation. The extra commitment required of the GM sometimes makes it hard to get anyone to agree to take on the role of Game Master, but that problem isn’t as common as you might think. The additional responsibility of being GM comes with a lot of creative control over what happens in the game. Just like many actors try their hand at directing at some point, many role-players eventually decide they want to give Game Mastering a try.

If you’ve decided to GM a game, either to flex your creative muscles or because you somehow got suckered into it, your first step in the journey is reading the Game Master materials for the game you’ve chosen. For some games, this requires buying a book (or multiple books) meant just for the GM. Other games include GM information in the core rulebook. In either case, the GM section or book(s) will contain a lot of game-specific information, from special rules that the players don’t have to worry about to game world secrets that the players aren’t supposed to know. Most also include some information about how to be a Game Master, but it’s often very specific to the game or rules set being used.

Even gaming guides that provide general Game Master advice often focus on tips and techniques without really describing the basics of GMing. Some of these omissions are due to the fact that games that are not specifically targeted to new players often assume an audience with at least some gaming experience. Other things are left out because what seems obvious to the kind of experienced gamer who writes games isn’t as readily apparent to a new role-player. What follows is my attempt to describe the most important “unspoken rules” that every GM needs to understand in order to run a successful game.