I wrote a long post about the differences in resolution mechanics between various kinds of RPGs, but it evolved into this. So I rewrote it.
I think computer RPGs need emotional interactions.
A big part of any adventure is the emotions felt during that adventure. Even a solo adventure is made interesting based on the emotional responses of the main protagonist. But in games right now, that doesn't exist.
Oh, sure, you can script it. But you can't actually play it.
The thing is, if you look at tabletop games... okay, this is a bit complicated, let me see if I can simplify it.
Most rules in a tabletop game exist to give you a foot hold within your party and against your world. The rules help tell you which role to play, so you can get in there and play it.
In combat, this role is a tactical one. You're the squishy mage, you're the tank, you're the fast character... the contrasting elements of each character dictate the kind of tactics you need to use. Even if you don't have a proper tank, the most durable character de facto becomes the tank when necessary... and the party's overall tactics will revolve around their lack of a good tank. The rules allow each member of the party to understand the role they should be playing relative to each other, and their combined role relative to the world.
But noncombat rules have the same exact purpose.
Your race, social class, noncombat skills, history, personality and alignment all exist to help you find your role quickly, so you can focus on the meat of the game. On paper, we tend to consider these things out of context, as kind of absolute skills or alignments. But in the game world, they are always relative to the world and especially the other characters in your party.
For example, a woodsie elf and a big-city rogue are in the same party. They go into a city. The big-city rogue is right at home in the city, and it is a hook, an inspiration which allows him to immediately get to work. He sells some stuff, buys some stuff, asks the local pick pockets for information, visits the crime boss, whatever you like. Each act can form the basis for another act which binds his character more tightly to the world. If left entirely to his own devices, it would be pretty reasonable for him to steadily create a chain of events which binds him ever more tightly to this city, perhaps ending up as a minor crime boss himself within a week. That's without any external adventure hooks - it's all just him being inspired by the last things he did and doing something in tune with them, but more aggressive.
The woodsie elf isn't there to just watch, though. The elf is a fish out of water, not good in cities, doesn't understand them. So when the rogue does these city-aligned actions, the elf knows his role is directly the opposite. He's there to be awful at being in the city. So he takes the opposite kinds of actions. When the rogue questions pick pockets for information, the elf might hang around behind him and get his pocket picked, or clumsily try to question them but end up accidentally propositioning an undercover cop.
The elf wouldn't just walk into the city and start questioning pick pockets. There's no inspiration that leads to that. Similarly, the rogue wouldn't walk in and just immediately become a crime lord. There's no chain of events leading to it. It's all about the recursive behavior: the rogue looks at his last action and says "more in tune with the city than that? Okay." The elf looks at the rogue's actions and says "that's in tune with the city, I need to do the opposite, bungle it up somehow." Then the rogue might say "Okay, the elf bungled it up, I have to go in and see if I can rescue this guy, oh, but now he's been arrested..."
Without any plot arc, just the interactions of the characters and the world can build an interesting adventure.
It's all about understanding the contrast between the characters, and using the inspirations provided to you (by the world or other characters) to take a suitable action.
That's emotion, too.
No, wait, I think I skipped some stuff.
In our computer world, we don't need to actually simulate emotion. We're not trying to model realistic characters. We're trying to create an adventure.
So our emotions are simple responses to simple stimuli, and they exist to help us contextualize in-world actions. Of course, many in-world actions are going to be complex, so that simple response will end up complex and multi-layered because the event is also complex and multi-layered.
For example, our elf and our rogue leave the city and enter the forest. The elf is happily humming. It's a very simple in-world bit of ambient activity that helps to build the sense that both characters exist in the same shared world. The elf wasn't happily humming in the forest before the city: this happiness is due to the contrast between the city and the forest. Similarly, if you now return to the city, the elf will be pretty unhappy about it. The first time he was curious but skeptical... this time, he'll probably refuse to go in unless you really cajole him. The city has been darkened by his experiences, the forest brightened, and now the contrast is much, much stronger.
The rogue can respond to any and all of the elf's emotions. These are simple responses varying from simple comments ("you seem happy!") to basic cajoling ("we have to go back in the city, come on.") There's no need to add complexity: the elf's complex inputs will automatically make the output more nuanced as the elf gets shy or enthusiastic or grumpy... all with close-ups of his face, of course, so the player can tell.
This is role playing. The social rules determine the kinds of actions that the characters will want to take, but also determine the kinds of things that make them feel various kinds of emotions. While in a tabletop game these rules are left loose and vague to give the players freedom, in a computer game they need to be as precise as combat rules.
If the characters have the same social rules parameters (for example, two elves from the same elf village) they are going to end up controlled mostly by their limited ability to engage the world, with their interpersonal interactions being relatively bland. Their few differences will generally end up being the texture needed to help them form a good relationship, even if the primary difference is which one is in the lead. The recursive nature of things will turn even those bland responses into a more nuanced ongoing relationship.
If the characters have diverse social statistics, they will be able to engage the world in pretty much any way they please, and the focus of their relationships will be on the differences between them. They'll have much punchier, hard-hitting relationships built on much more solid foundations, and those solid foundations will probably serve as a basis even as their relationship begins to recurse.
Either way, the result would be a very adventure-feeling adventure.
Sounds good... but is it actually possible?
I dunno. Maybe I'll rough out some specific rules.
The key is that there's no "relationship value" that increases or decreases. Everything is recursive. Your relationship is the repeating social output that feeds into the same algorithm with each new social event.