I don't bother defining good or bad. I give the NPCs motivations/impulses and goals/desires.
Likewise.
mimesis is the representation of an internally consistent game world that is portrayed according to its nature (along with any elements therein).
And that for purposes of RPGs, diegesis is the assumption of narrative control outside of the mimetic frame.
So you have a world that, by default, operates according to its nature except where a player or DM exercises some power to author the situation.
This is an interesting conceptual framework.
Translating it into my own terms that I'm more familiar with, I relate your "mimesis" to my sense of genre expectations plus "common sense" determining the general course of events, with the GM's authority to frame situations and narrate outcomes in accordance with the action resolution mechanics providing the "diegnesis" component of interjected content.
I wasn't clear enough when I said he was spared by Deus ex Machina. See, he chose death rather than evil and dropped what is established as a lethal distance (functionally bottomless).
<snip>
If Luke was my player, and I present him with a choice of falling down a bottomless pit or conversion to evil, I should NOT give him the odds of survival. I want Luke's player to decide what to do based on the situation & circumstances, not the rules and math. If Luke chooses death, I may well take narrative control and let him slip down a chute and get stuck in a pickle from which he may or may not escape. I may kill him. In either case, using the system has not added anything to this moment. That doesn't mean the rules are broken. It means they don't apply here and shouldn't reasonably be expected to. The "right story" is the one that's created by the diegetic action (the departure from the true nature of the game world).
Luke's player, beaten within an inch of his life, looks at me and says "I'd rather die," then let's go and falls. I need to honor that decision somehow. And the system is too heartless, too arbitrary, and does not match the frickin metal Luke's player just laid down. The right story matches that metal.
An interesting example.
The closest I can recall coming to this scenario in actual play was around 6 years ago, at the climax of a long-running Rolemaster campaign. The PCs had finally achieved their goal of entering into the outer void to defeat an elder evil who resided there. The evil being had been held at bay for eons by the efforts of a warrior god, who in the mortal world was a dead god, having heroically sacrificed himself to prevent the elder evil breaking through the walls of reality, but who in the parallel dimension of the outer void was locked in an eternal struggle with the evil being, forever suffering and dying without relief. The PCs has first encountered echoes of the dead god around 10 or more levels ago (so probably 4-odd years of play earlier) and they had been a recurring feature in play and an increasing focus of the players' efforts. One of the PCs in particular - the paladin - had become dedicated to freeing the "dead" god from his entrapment in the never-ending voidal war.
So when they broke through into the void, and beat the elder evil, they knew it couldn't last. They couldn't escape the eternal cycle of entrapment anymore than the dead god could. And so, in order to free the dead god, the paladin decided to take his place. And this was a free and deliberate choice by the player of that PC, to sacrifice his character in order to end the suffering of an NPC, the dead god.
Then we reconvened for the next session. And the players had been discussing, and discussed further during the session, and they came up with an alternative plan: first, the PC wizards would pool their spell abilities to create a simulacrum of the paladin (this was straightforward spellcasting mechanics, though in a moderately intricate combination - in 3E terms think a subtle combination of spells and meta-magic effects); then, they would trick a fallen Lord of Karma into using an artefact they had custody of (the Soul Totem) to create a full karmic replica of the paladin in his simulacrum, so that it would have the metaphysical capacity to take the dead god's place in the eternal fight within the void.
Tricking the fallen Lord of Karma was again mechanical in resolution (using the game's social mechanics) but using the artefact in that way was not mechanical. The artefact was a story element with no mechanical definition, and the players' plan was an extrapolation from that established story. As GM, I had to decide whether or not it could work. And I decided that it could - the extrapolation was a natural one that followed completely naturally from what had gone before, and to decide otherwise would actually have contradicted pre-established story elements about the function of the artefact and the reason the various Lords of Karma had fallen in the first place.
So the campaign had a happy ending rather than a sad one: the "dead" god was freed from the void, his place taken by a karmically-laden simulacrum. The player of the paladin was able to narrate his PC's endgame in the more idyllic terms he had hoped for, of founding a monastery dedicated to the dead god, located in what had been a lighthouse built on an island that was in fact the giant "stone" body of the "dead" god in his final resting place on the mortal world before entering into the void.
Let's leave Luke and assume Vader is the PC. Vaders goal is recruitment of his son, and accumulation of power. He's defeated Luke (an NPC) and put him in a bind. Does Vader's player roll to see whether Luke joins him? Is that what diplomacy checks are for? I don't think so. So I don't dip into the rules. Instead, I rely on Luke's nature. Vader tells me he wants to seduce or manipulate Luke into joining him. And, he's clearly got leverage. Luke's beaten and has no escape route. However, I know Luke cannot be corrupted in this way and Vader doesn't even get a cha-check. This is an auto-fail. I simply play Luke true to himself. He falls. Vader's player curses as he's just let his whole goal slip from his grasp. This could be game over for Vader, but later, I tell him he senses his son in the force, alive, and reaching out for him. I've played Luke mimetically, and then turned diegetic to re-up Vader's player on his quest. I turned a total fail into a setback. Vader redoubles his resolve. No system.
On this example I think I'm closer to [MENTION=22779]Hussar[/MENTION]. I would be hesitant to narrate an auto-fail for the player, even with the sort of backup option you describe.
The closest I've come to this was in
a session earlier this year. The PC, a servant both of Vecna and of the Raven Queen, had taken temporary control of a pool of dead souls. He was expecting them to begin flowing to the Raven Queen, but then became aware that Vecna was trying to intervene and steal them. The medium that Vecna was using was the PC's imp familiar, which had the Eye of Vecna implanted in it. The player had to choose whether his PC let Vecna have them, or redirected them to the Raven Queen. He chose the latter. And (as GM) I decided that Vecna punished him by channelling his fury through his Eye, killing the imp.
One consideration that was crucial to my decision was that the player knew that he was choosing to cross Vecna; knew that the Eye was in his imp and that Vecna was using this as a conduit; and had [urhttp://www.enworld.org/forum/showthread.php?348410-Should-this-PC-implant-the-Eye-of-Vecna]deliberately implanted the Eye in his imp rather than himself[/url] precisely to be able to draw upon its powers without running the risk of being punished by Vecna himself.
If your Vader scenario had these sorts of elements, I might adjudicate more along the lines you describe.
I still don't call for rolls when actions will automatically succeed or fail. I just say what happens next. In this scenario, Luke cannot be seduced or manipulated in the fashion Vader attempted.
Vader's Player's problem wasn't his planning or his execution - all those things were well thought-out and competently executed. The failure was in misunderstanding the character of NPC Luke. Vader offered power when the available evidence suggested Luke's motivation was care for others. (Heck Vader's trap was baited by torturing Luke's friends). Vader's Player ought to have known better, but failed because he overplayed his hand.
This all relates to the same point - player knowledge. I would be hesitant to have the player learn whether or not his/her plan can succeed, in virtue of the gameworld backstory, only at the point of resolution. I generally prefer to have the players make their choices against a backdrop of known story elements, but in which they can't achieve everything they want (or, at least, not easily or obviously).
In your most recent posts discussing player knowledge with [MENTION=4937]Celebrim[/MENTION], I agree with what you're saying.
Leave Vader aside. Can a non-magical class cast a spell if the dice come up right? Or is it impossible?
Can a character with +50 in athletics jump a mile or is it impossible? Can he fail to jump a foot? Or is it automatic?
Do you allow for any action to have automatic success or fail conditions - or is that all failure of imagination?
In these cases the players have knowledge. The question of player knowledge is important for me.
