Setting is, to my mind, utterly essential to RPGs, and has also been the poor cousin to rules design in a lot of the deeper discussions of RPGs. I’m not entirely sure how to address that, but I think a good start involves looking at setting design with the same eye we’ve applied to rules, and see what we find.
On my mind at the moment is the question of what makes a setting particularly playable. This is not the same thing as what makes a setting good or compelling, and in fact, a good, compelling setting can end up making a very good game even if it has no elements that make it more explicitly gameable.
While this is far from a comprehensive list, these are the elements that float to top of mind for me.
Unless the setting implicitly keeps the entire group of characters within shouting distance (something dungeons do) then they need some means of staying in touch. In the absence of this, you can end up with difficult pacing problems if the game starts going one particular direction without one or more players participating. Communication (and its companion, ease of travel) is the solution for this. Modern games have an easy solution to this with cell phones, but things like Amber’s trumps can fill this purpose as well.
As a paradoxical bonus, the presence of a communication element is necessary to make the absence of communication into a plot element. Running from zombies and trying to find cell signal is something you can’t do in 1974.
If your game is going to have any amount of violence, then you need some way to keep long hospital trips from bogging down the game, you need some logic to address this. It might be a genre thing (as in cinematic or supers games), or it might be an element intrinsic to characters (like Vampires and Amberites) or some easy means of healing (like spells or some magical substance); whatever the form it takes, the real purpose is to keep play moving.
The exact means of recovery may also be a plot element in its own right, so its worth considering that this doesn’t exist in a vacuum.
This can take a lot of different forms, but it is best described as characters having a role in the setting, something that has a context beyond themselves, but still of an understandable scale. A family or secret society might fill this roll, but a nationality won’t because it’s simply too big.
The litmus test for this is whether or not it helps answer questions about what the character does and has done “off camera” and how well armed they are to answer questions and make decisions without a full GM briefing. That may not seem intuitive, but consider that the social context provides resources with faces - people who you can talk to and turn to in complicated situations. Not only is that play generating, it creates a virtuous cycle where that play reinforces social ties, which in turn allow fodder for more play.
However, one needs to be careful to keep contexts playable. It is structurally better to have everyone within the same context, or at least within one context, otherwise the context draw away from play. Consider the problem when every player is an agent of a different group - you can construct something artificial to tie them together, but it’s tricky to maintain. Easier to either use different groups or subgroups. Consider these examples:
- In Vampire, characters were members of their clan, but they were also part of the political structure of their city. The latter could help bring a group together without the former completely pulling them apart.
- In Eberron, the Great Houses were really interesting and colorful, but they were potent enough ideas that they wanted to pull the game in their own direction. Unfortunately, because it was paired to the power system, it was easy to end up with things pulling apart.
- Amber has the family has an overarching group, but it has numerous shifting factions and alliances within that group.
Mobility or Position
This is not literal mobility (though that has a place, as noted under communication) but rather social (or social-ish) mobility. Characters need to have the opportunity to change their situation through their own efforts. Partly this is something that helps buy into the context of the setting, but it’s also a big avenue for player-generated plots - if they have something they want that they can get, then sooner or later they’re going to get motivated to go after it. It’s also worth noting that while this may interact with character advancement, there’s no guarantee that it will.
The alternative for this is to give the players position (and with it, responsibility). It’s a similar play motivator, just from the other end. People like being important, and important people have things to do.
There’s no reason a setting can’t have both of these, but one or the other will suffice.
I am by no means asserting that a game can’t be fun without these, or that a setting can’t work without them, but I know that when I sit down to scratch out a setting (or even a sub-part of a setting) for a game, these are the things I try to make sure are present.