Having Arduin do a lot of my thinking out loud is very helpful. But I think we're beginning to deviate enough that it's worth throwing in my own thought processes ... though I admit this topic, that of an interaction mechanic, is beginning to resemble the further scourging of a mortified equus.
I do not have any playable mechanics to suggest. And without criticizing those mechanics suggested by Arduin and James, I have to say that I've long abandoned any hope that an existing deck of any kind can be grafted onto a D&D template. There are just too many limitations; the suits or the arcana of either the standard deck or the tarot deck are straightjackets and are not convenient for what I've had in mind.
And what is that? I've alluded to the answer, but I haven't made it clear. The deck would have to be of a very particular nature, one that doesn't exist (in my opinion). In all honesty, the creation could be a significant money making proposition ... so I suppose by writing it here, on this blog, this January 20th, I'm setting myself up for a long and failed court-visit sometime in the future. If this is as practical as I think it could be.
The primary issue must not be that a problem is gotten past, but that the player gains an ally ... some individual who is sympathetic to the player's needs. Some allies would be dependent on money - the bribed guard, for instance. Some allies on friendship. Some on fear. The player would be using their influence, step by step in the game, to work these allies towards their own purposes: a savings when buying at this merchant's shop; news about the goings on at the guild; physical aid in times of danger; supplies; reliable messengers; and so on. Each interactive process would play to create a given morale on the part of the ally, which would be fixed by the IMech as best as the player could ... but without the guaranteed yes/no of a skill roll. It's the result that makes the dynamic playability of the IMech, not the process. The result that says, today, the bribe will work, but tomorrow, the guard might have second thoughts.
Towards this idea I see a very wide range of different types of cards. Yes, there would be a card - one card - each for charisma, wisdom and intelligence. I think the idea of having the player roll against their attribute when the card is played, to see if it 'works' ... I am assured by my source in the Magic card game that various cards do work like that. I also think there would be a card for certain charisma-rich or intelligence-rich classes - mage, paladin, druid, bard, cleric and so on. Being a religious figure carries with it a certain dignity and prestige that ought to be noted in the system.
But the lion's share of cards would not be based on the character's stats at all, but upon what the player has actually accomplished up to a given point. For example, there would be a card that would be gained the first time the player had gotten into a battle in which he or she had gotten wounded: a sort of 'purple heart' card.
I see a range of cards all based on first time experiences. The first near death moment; the first time the player had been at sea (out of sight of land); the first dragon the player had seen; the first dungeon; commanding men in battle; the first time the player had ever rescued a stranger from the grip of death; and so on. These things have their lasting impression on an individual, and provide stories for a person to tell, at the Inn or elsewhere, giving them insight into what frightens a person or what taps into a person's imagination or ambitions.
Every time that a player does something significant, the card would be gained; and the card could then be played in order to master the environment. I see the whole process as a kind of "scout's badge" motif. People talk of 'carrots' to encourage certain kinds of roleplaying and character development ... this is exactly that.
The cards would have to be particular to the design of the character. A character wishing to get into the good graces of the underworld would hardly do it by providing a military unit to the town. An assassin, on the other hand, might want the drunkard card, as it would help them pass openly in the worst places as someone not to be concerned about.
Unfortunately, the cards would have a limited scope. Known as a drunkard in one town would not necessarily correspond to everywhere. Which brings up a point that I know someone will propose - that cards aren't needed. That the character can just write all this on their character sheet.
Of course they can. But the cards represent things the character sheet cannot provide:
1) The presence of the cards put front and center things that tend to get ignored on character sheets. Being able to rift through the cards - in fact, having to do so - brings the different cards to the character's perception in the way a character sheet does not. A scout troop could just keep a book that says what scout has earned what badge - but the ostentatious portrayal of the badge display provides a reminder.
2) A list of things on several character sheets does not have any particular emotional impact; but to use the scout badge metaphor again, the collection of cards provides a sense of accomplishment, a sense of pride, and a demonstration of prestige. It is the fetishistic quality of having the cards in one's hand. Let's face it, a painted lead miniature has held that place in the game since the beginning.
3) Once an interactive mechanic has been worked out for how players can 'battle out' their roleplaying prowess, the cards exist as a convenient tool.
Now, as a last point, and this is the kicker. These cards would have to be manufactured. They would have to be attractive to look at. And they have the added bonus of constant expansion, as people dream of new things to give cards for, new badges to be won, stacked and played with.
Plagiarism of a business model, anyone?