I've always thought it would be cool if a dialogue system similar to The Elder Scrolls or Mass Effect had a way to apply a range of attitudes to responses. I haven't seen any games that have done this, although it wouldn't surprise me if one is out there. My idea was to create the tree of responses as being neutral and the player can manipulate a slider (or some other visual UI) to apply certain ranges of emotion to the responses and the NPC's dialog tree would take these cues into consideration and react accordingly. So instead of the usual 4 responses where each has a general attitude the player will only get a few basic neutral responses and will have to apply the emotional attitude themselves. Then there could be a deeper conversation tree that will fetch the "spoken" (show as being actually said to the NPC) response that is appropriate to the attitude chosen (if that makes any sense, I'm really tired).

While this has all been terrific, I guess I'm more interested in hearing what you all have to say about a game in which the core game mechanic IS the game's dialogue. I keep on getting the sense that one could make a game where a person can somehow gain skills and abilities in dialogue, improve their skills in aspects of it, and somehow come to develop an interest in deeply analyzing the decisions they make within it. Can anyone else envision details about what such a game might look like, how it might work, or in what ways it might be able to reel in a player's interest?

Hmm, here's an idea. So the balancing act in designing a "gamey" dialogue system, I think, is that the player either knows what words their choice corresponds to -- that is, they see their utterance ahead of time, or they don't. (That is, they see "Agree" or "Sarcasm" or "Threaten" rather than the utterance that the choice will actually produce.) With the former, they'll just treat it like any other dialogue system, I think; with the latter, there's the frustration and loss of immersion when the words chosen aren't what the player anticipates. (Like we might be in a negotiation, and I might think the best tactic is applying some subtle pressure, but then choosing "Apply pressure" causes the PC to threaten to kill someone's family. That reminds me that I'm playing a game, and also that it's a game written by idiots.)

A happy medium might be if different rhetorical strategies are represented by different characters in the player's party: an earnest farmboy, a haughty noblewoman, a blustering mercenary, a snarky thief, a flirty spy, etc. When you ask someone something, you choose both a topic of conversation AND which character should present it. So as you gain characters, you gain a wider variety of conversational abilities, like a dialogue-centric Suikoden.

It comes down to predictability. The player can roughly predict what effect specific utterances will have. The player can't predict what effect choosing "Sarcasm" will have unless they know the actual utterance. But once the player knows and understands character X, they can kinda predict the results of "Let's send X to ask about Y."