One of my kids likes to play imagination games - she and her friends all pretend to be other people (often superheroes) and do exciting and interesting things.
These clearly have a lot in common with RPGing. But they don't have rules - disagreements about what happens next are just resolved by people talking it over and reaching (or sometimes not reaching) agreement.
So why do RPGs have rules?
Some of the best answers to this question that I know come from Vincent Baker (here, here and here):
In summary: on this account, the function of RPG rules is to help mediate and constrain the process of agreeing on the shared fiction; and not just by assigning authority ("It's your turn now to say what happens next") but by shaping what is said so that it is surprising and even unwelcome to all participants.
There are approaches to RPGing, and examples of RPG rules, that at least to me don't seem to fit with Baker's picture. That doesn't necessarily make them "bad" RPGs. It does mean that they are meant to provide a different sort of experience from what Baker has in mind.
The two examples I'm thinking of:
(1) In classic dungeon-crawling and puzzle-solving D&D, some of the rules do have the function of easing negotiation - eg rules about likelihoods of finding secret door, and rules about surprise and encounter distance, and some elements of the avoidance and evasion rules. But some of the rules really seem like they're largely disconnected from "shared imagination" except that, at the end of the rule process, they spit out an answer to "what happens next" - I'm thinking about the combat rules in particular here, which involve playing a mini-wargame to answer the question "what happens when the PCs fight the monsters". And the idea of "unwelcome" outcomes doesn't really seem applicable.
(2) In "trad", post-DL D&D, the general expectation is that the players will work through the GM's scenario or story. There are non-D&D PRGs, like CoC, that are played similarly. Some of the rules in these RPG do seem to have the function of easing negotiation - eg Perception checks or Research checks will determine when and how the GM dispenses new information to the players - but the rules don't seem to have any function of generating "unwelcome" outcomes. In adventure modules intended for this sort of play, there are often instructions to the GM about how to blunt outcomes that might be unwelcome (eg if a Perception check is failed, here's another way to provide the new information; if a NPC is killed, here's a way to introduce a new NPC to play the same role as the dead PC would have played in events that are yet to occur in play but are intended to occur as part of the scenario). I would say that an important role of mechanics in this sort of play is to generate a degree of uncertainty on the part of the players about the exact process that the GM is using to determine what happens next.
There are probably other reasons too why RPGs have rules, other things that those rules can do.
These clearly have a lot in common with RPGing. But they don't have rules - disagreements about what happens next are just resolved by people talking it over and reaching (or sometimes not reaching) agreement.
So why do RPGs have rules?
Some of the best answers to this question that I know come from Vincent Baker (here, here and here):
Roleplaying is negotiated imagination. In order for any thing to be true in game, all the participants in the game (players and GMs, if you've even got such things) have to understand and assent to it. When you're roleplaying, what you're doing is a) suggesting things that might be true in the game and then b) negotiating with the other participants to determine whether they're actually true or not. . . .
Mechanics might model the stuff of the game world, that's another topic, but they don't exist to do so. They exist to ease and constrain real-world social negotiation between the players at the table. That's their sole and crucial function.
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Some very good designers consider the assignment of authority to be the point of rpg design. I do not.
As a designer, it's my job to make as sure as possible that the game won't break down into moment-to-moment negotiations about raw assent despite the game's rules and the players' upfront commitment to them. But the brute assignment of authority is NOT how to accomplish that.
When my games assign authority they do so in strict service to what I consider the real point: setting expectations and granting permission.
*********
if all your formal rules do is structure your group's ongoing agreement about what happens in the game, they are a) interchangeable with any other rpg rules out there, and b) probably a waste of your attention. Live negotiation and honest collaboration are almost certainly better. . . .
As far as I'm concerned, the purpose of an rpg's rules is to create the unwelcome and the unwanted in the game's fiction. The reason to play by rules is because you want the unwelcome and the unwanted - you want things that no vigorous creative agreement would ever create. And it's not that you want one person's wanted, welcome vision to win out over another's - that's weak sauce. No, what you want are outcomes that upset every single person at the table. You want things that if you hadn't agreed to abide by the rules' results, you would reject.
If you don't want that - and I believe you when you say you don't! - then live negotiation and honest collaboration are a) just as good as, and b) a lot more flexible and robust than, whatever formal rules you'd use otherwise.
The challenge facing rpg designers is to create outcomes that every single person at the table would reject, yet are compelling enough that nobody actually does so. If your game isn't doing that, like I say it's interchangeable with the most rudimentary functional game design, and probably not as fun as good freeform.
Mechanics might model the stuff of the game world, that's another topic, but they don't exist to do so. They exist to ease and constrain real-world social negotiation between the players at the table. That's their sole and crucial function.
*********
Some very good designers consider the assignment of authority to be the point of rpg design. I do not.
As a designer, it's my job to make as sure as possible that the game won't break down into moment-to-moment negotiations about raw assent despite the game's rules and the players' upfront commitment to them. But the brute assignment of authority is NOT how to accomplish that.
When my games assign authority they do so in strict service to what I consider the real point: setting expectations and granting permission.
*********
if all your formal rules do is structure your group's ongoing agreement about what happens in the game, they are a) interchangeable with any other rpg rules out there, and b) probably a waste of your attention. Live negotiation and honest collaboration are almost certainly better. . . .
As far as I'm concerned, the purpose of an rpg's rules is to create the unwelcome and the unwanted in the game's fiction. The reason to play by rules is because you want the unwelcome and the unwanted - you want things that no vigorous creative agreement would ever create. And it's not that you want one person's wanted, welcome vision to win out over another's - that's weak sauce. No, what you want are outcomes that upset every single person at the table. You want things that if you hadn't agreed to abide by the rules' results, you would reject.
If you don't want that - and I believe you when you say you don't! - then live negotiation and honest collaboration are a) just as good as, and b) a lot more flexible and robust than, whatever formal rules you'd use otherwise.
The challenge facing rpg designers is to create outcomes that every single person at the table would reject, yet are compelling enough that nobody actually does so. If your game isn't doing that, like I say it's interchangeable with the most rudimentary functional game design, and probably not as fun as good freeform.
In summary: on this account, the function of RPG rules is to help mediate and constrain the process of agreeing on the shared fiction; and not just by assigning authority ("It's your turn now to say what happens next") but by shaping what is said so that it is surprising and even unwelcome to all participants.
There are approaches to RPGing, and examples of RPG rules, that at least to me don't seem to fit with Baker's picture. That doesn't necessarily make them "bad" RPGs. It does mean that they are meant to provide a different sort of experience from what Baker has in mind.
The two examples I'm thinking of:
(1) In classic dungeon-crawling and puzzle-solving D&D, some of the rules do have the function of easing negotiation - eg rules about likelihoods of finding secret door, and rules about surprise and encounter distance, and some elements of the avoidance and evasion rules. But some of the rules really seem like they're largely disconnected from "shared imagination" except that, at the end of the rule process, they spit out an answer to "what happens next" - I'm thinking about the combat rules in particular here, which involve playing a mini-wargame to answer the question "what happens when the PCs fight the monsters". And the idea of "unwelcome" outcomes doesn't really seem applicable.
(2) In "trad", post-DL D&D, the general expectation is that the players will work through the GM's scenario or story. There are non-D&D PRGs, like CoC, that are played similarly. Some of the rules in these RPG do seem to have the function of easing negotiation - eg Perception checks or Research checks will determine when and how the GM dispenses new information to the players - but the rules don't seem to have any function of generating "unwelcome" outcomes. In adventure modules intended for this sort of play, there are often instructions to the GM about how to blunt outcomes that might be unwelcome (eg if a Perception check is failed, here's another way to provide the new information; if a NPC is killed, here's a way to introduce a new NPC to play the same role as the dead PC would have played in events that are yet to occur in play but are intended to occur as part of the scenario). I would say that an important role of mechanics in this sort of play is to generate a degree of uncertainty on the part of the players about the exact process that the GM is using to determine what happens next.
There are probably other reasons too why RPGs have rules, other things that those rules can do.