One of the most important and least-discussed elements in a successful game is a shared set of assumptions about how and why the game is played. But many gaming groups want to jump straight to “the fun stuff” without making sure that everyone shares the same definition of “fun” (or even the same definition of “stuff”). A few minutes or even hours spent ensuring that everyone at the table agrees with (or at least is comfortable with) everyone else’s assumptions will prevent some potential disasters  down the road.
We roleplayers will spend more time discussing (arguing) the rules of the game than any rabid sports fan. To an outsider, this may seem odd: For a game based largely in the imagination, those gamers sure do focus on the rules a lot. But we know this makes sense, in that the rules are the framework on which our dreams are hung, and are capital-i Important.
Rule differences can be settled by GM fiat, voted on, researched, brought to the author of the game, etc. But when my unwritten (and often unexamined) assumptions of the game clash with those of others at the table, there’s no court of higher appeals; we’re left wondering why that other doofus can’t see what’s blindingly obvious to us. And you can bet dollars to donuts that he’s doing exactly the same to us…
There’s been a lot of ink and pixels spilled on discussions of the “Social Contract” in gaming. Personally, I dislike that phrase; it’s already in use in at least two other disciplines, and carries a number of connotations that I don’t think belong in gaming. I don’t claim to have a better alternative; “Ground Rules” is too vague and “Gaming Compact” sounds like a pocket-sized rulebook. But whatever we call it, whether it’s written down or just talked about, the social contract is something that should be discussed and agreed upon before the dice roll.
Gamers aren’t famous for their communication skills, but this discussion is one where we all need to be on our best behavior. A lot of what’s being discussed is very subjective, and some of it can be personal.
A group needn’t spend hours on this. In any social situation, small groups of people will establish their own ground rules over time as various situations arise and are dealt with. It’s only in odd places like a gaming table that this becomes a bigger issue, because at the beginning of the game players will spend hours planning out character development and progression, background stories, motivations, etc, and GMs will spend hours spinning plot arcs, NPCs, expected actions by the players, etc. When it becomes obvious that these “shared assumptions” aren’t shared (and sometimes aren’t even assumptions), a lot of time and effort has been wasted, and it can be frustrating trying to find common ground.
OK, so we need to talk about our game before we play it. Now what? Some obvious non-game topics include: how meals should be handled, whether or not (and how much) alcohol is acceptable, tobacco use (and other, um, stuff), respect for the host’s house and family, respect for other players and their opinions, how absences are handled, etc. Some of these are mundane and almost silly, but you can bet that Murphy  will find the one thing that wasn’t discussed.
Some of the easier game-related topics may include expectations of integrity, character generation, how combat is managed, who settles rules disagreements (and how quickly), and what tasks the GM expects from the players (record keeping, etc). Most groups settle this stuff pretty quickly, or handle them as they come up in-game.
The larger problems that I’ve seen are the more complex and subtle issues of in-game assumptions, and this is where I feel the bulk of the discussion should take place. These include defining the genre, appropriate character behavior, and what the players and GM seek to gain from the game.
Defining the genre is important, because “Heroic Fantasy” may mean completely different things from player to player. Talk about what the terms mean, and use specific examples. Conan the Barbarian  and Final Fantasy  are both medieval fantasy, but there will be some grinding of the gears if you try to mash them together. Any group will usually have some compromises to hammer out, and this is definitely the time to do so.
This is also where the mood or tone of the game is handled; again, use specific examples. Does ‘grim and gritty’ merely mean that magic is hard to find, or does it mean that you should roll up a half-dozen replacement characters for the first session? Something in between? Talk it out.
Finally, GMs should remember to clear their ideas with their players; I wish I had a dime for every GM who wants to run a ‘grim and gritty’ game, but whose players want to run famous and powerful heroes. Find the middle ground, or at least let everyone know what your tastes are.
Directly related to genre is appropriate character behavior; it wouldn’t be a Final Fantasy game without some internal clashing. Some roleplayers think that intra-party conflict is the best part of gaming; others find it destructive to the well-disciplined team that they want to be a part of. Most of us are somewhere in the middle, but few of us see it exactly the same way. GMs should talk with the group about what kind of character behavior they think is appropriate, and should listen to the rest of the group as well. Players should be honest about what kind of character behavior they find appropriate.
Which leads us to “What do you want from the game?” Roleplaying gaming covers a lot of territory, from improv theater to tactical miniatures to investigations into metaphysics and philosophy to internal examinations of morality to outlets for frustrated authors. Some of these are wholly compatible, but some may make people uncomfortable. We all want different things, so before those dice start rolling, take a few minutes to talk about it, and see what can be worked out before the group turns on itself and the game grinds to a halt.