So, I don't think Thousand Year Old Vampire actually presents that much of an issue. I think it is at least reasonable to consider it a game, as it is certainly a pastime, it involves elements of following a rule or process, utilizes specific devices, and involves specific types of participant inputs which contribute to an outcome. Understandably there isn't a 'score', but this is also mostly true of other RPGs, so I don't think it excludes TYOV from being an RPG. It has a somewhat unusual allocation of WHERE it locates its 'open-ended nature', which I think is a fairly significant feature of most RPGs (IE the trait of allowing for fairly arbitrary responses in which fiction plays a key part). Yet TYOV DOES have an open-endedness, you can write pretty much any journal entry which explicates the prompts and follows from previous fiction. So it is a sort of 'fortune first' kind of design, prompts are generated, and then at the end fiction is generated which conforms with the mechanical state changes required by the prompts. It is a bit unusual in the sense that its a fairly passive process, the player is writing the fiction, but not actively leveraging the fictional position as they might in more typical RPGs. I think it is less different than people might first think though in that you DO leverage game state, your fiction cannot reference resources you no longer possess for instance (IE you cannot explain the latest state change by alluding to your employment of a resource you have already given up in a previous turn).
So, what is the agenda, that's the question.
1) Is it gamist? I guess you could play to see how long you can stay alive, but in that case the fiction is pointless and the game is just an exercise in taking a random walk, it has exactly the skill demands of Chutes and Ladders. So, its a lousy game, IMHO and I'd not consider that to be a focus.
2) Is it Narrativist/Story Now? Well, STORY does seem to be the POINT in that the object of the game seems to be to produce a journal or experience the production of a journal, though you could see the journal as more of a 'focusing device'. You could simply imagine to yourself what happened at each step, but if you don't write it out nothing really crystalizes it. I think that's because of the solo nature of the game, the journal acts a lot like what happens when you share fiction in a standard RPG, it becomes canon and acquires a more concrete nature which can be the springboard for the next turn. But in a GNS sense is it focused on dramatic needs and driven forward by them? Maybe in terms of the genre, yes. That is, your 'PC' is a Vampire, and has the motives and needs of such. I assume one of the principles of play is to RP "I am a Vampire" as I don't see anything in the game structure which otherwise forces you into that. So, we might consider the possibility of this game being a kind of 'setting driven' story now game.
3) Simulation? Well, it certainly doesn't seem to be much of a 'process sim'. OTOH in a sense it has some of this character where the inputs of the system are these absolutes. There's no real sense in which the fiction feeds back into the mechanics though, its all 'boxes to cloud' leftward arrows. However, the game does produce mechanical outputs which clearly work to introduce prompts to generate trope-appropriate fiction. Again, the principle of play "I am a Vampire" comes in here in a rather obvious way, the premise is quite explicit as far as I can see. So we seem to have a kind of High Concept/genre type of focus.
So, I'm not seeing where GNS has some huge problem with TYOV. I mean,
@Manbearcat,
@Ovinomancer, or
@pemerton may well disagree with me in how I interpret things, which may speak to a level of difficulty grasping GNS, but it seems capable of talking about this game at least. Nor do I see some major hole in the analysis, personally. At most perhaps it points at the division between High Concept Simulation and Story Now sometimes being a bit hard to parse, or even subjective. Perhaps they often form a sort of variation by degree, where at the extreme end you have some quite purist Story Now play, and at the other the focus has shifted almost entirely onto some premise that is not really character centered and less laser focus on character advocacy as a driving principle.
Finally, I differ from Pemerton in that I think it IS useful to look at outliers. Not so much in terms of 'can I construct a framework that handles this' as in terms of 'how general is this one'. So, I might not try to devise a theory of RPG agendas/play/design/whatever with TYOV in mind, but I feel perfectly comfortable analyzing it with an existing one and considering what that tells me about the power of the abstraction.