Is Vampire, Fate, Grimm, Summerland, Fantasy Heartbreakers, Westeros, Rolemaster...etc all D&D?
Summerland I don't know. "Fantasy Heartbreakers" isn't a game but a description of a style of game invented by Ron Edwards - they're not D&D per se, but by definition are derived from or react against D&D. The rest, not in my view. Their mechanics are different. Their tone is different. The experience of playing them is different. Subject to one qualification . . .
What if the campaign is set on Krynn and use the Fate system? Is it still D&D?
In my view, yes. D&D is a system. And it's a bundle of settings, tropes, themes etc. If someone's table is covered in books with "D&D" on the cover (eg Atlases of Krynn, DL modules, etc) then the fact that they're rolling those funny +/- dice rather than polyhedrals seems to me a secondary consideration.
There are limit cases - eg I thinkthe idea of DL GURPS would be as incongruous as was ICE's Middle Earth RM - it would be likely to depart far enough from the actual tone and themes of DL that it might be DL in name only and hence not really D&D.
Does one draw a line? Is there a line?
Whether one wants to draw a line depends on the motivation - we're not discussing natural kinds here!
From WotC's point of view - and their commercial motivation - they naturally want to draw the line one sort of way (that rewards "brand affiliation" that manifests through purchasing and/or contributing to networks that contain purcahsers).
From my point of view, WotC's commercial/brand strategy is an object of curiosity but not something that particularly motivates me (my livelihood isn't riding on it) - mostly when I think of something as D&D (eg because someone describes it that way) I think of mechanics and I think of fiction (various settings, monsters etc). If there's not much of either then calling it D&D may not convey much useful information. If there's lots of both then it's probably D&D in an unequivocal fashion. If there's lots of one but not much of the other then it may be D&D for some purposes but not others.
To give a practical example that relates to edition-variations: I know Night's Dark Terror pretty well. Whenever it comes up on these boards, [MENTION=29398]Lanefan[/MENTION] summons me into the conversation. But I ran it in 4e, not B/X. And I changed bits of the module - eg I replaced the module's ancient culture with minotaurs, because that fitted in with some 4e stuff I wanted to use; and the final, plateau encounter area was very different at my table from the published module.
Was that a "genuine" NDT campaign? By [MENTION=23751]Maxperson[/MENTION]'s standards, I would think not. But if someone wants advice on how to handle the encounter with the bandits on the river; or how to enrich the details of Threshold (one of the module's towns); or what might some good "side quests" look like, if they wanted to dilute the focus of the module a bit; or how to handle the story elements if you scale it up for higher level PCs; then I think I've got some useful advice to offer. And in that context, what would be the point of denying that I've run NDT? Of insisting that I've only run some
alternative or adapted version?
So your Fate group playing a game set in Krynn: if I wanted advice on how to make DL characters really sing, and what sorts of motivations they've found to work in play so that I can get something going like (say) the Tanis-Kitiara-Laurana triangle, then I would think they have something to offer. On the other hand, if I want advice on the best way to handle moon phases in 5e, maybe they dont' have so much to contribute. Again, asking whether or not it's a
real D&D game doesn't seem to have much value to me.
I feel if we don't actually have tighter definitions then D&D becomes a meaningless term or the statement I run a GH campaign = I run a Star Wars campaign = I run Dogs in the Vineyard
If I tell you someone;s artwork gives me a post-impressionist vibe, am I including the possibility of hints of cubism, or leaving cubism out? It might be a bit hard to know until we get further into the conversation, in so far as the relationship of continuity/disjuncture between impressionism and cubism is contestable and contested; but that doesn't mean that the language is useless. You can be pretty confident that the work they're doing isn't going to look much like Titian.
If I say my game is a GH game, you can be pretty sure it doesn't involve Dogs policing sin-laden towns (unless I'm doing a Murlynd special - the paladin of Boot Hill). But if you're not going to count it as "playing in GH" unless every bit of published canon is adhered to, how many GH games do you think are out there? And what bit of RPGing experience or community are you trying to communicate with, and about, by framing the use of a setting in such narrow terms?
The post of [MENTION=7635]Remathilis[/MENTION]'s that I replied to upthread said that "Canon should be the starting point for any discussion of lore". Why? If someone wants to talk about how they're using gnolls in their game, I want to hear how they're using gnolls in their game! Whether they're following Volo's, adapting Volo's, ignoring Volo's - that seems pretty immaterial to me except perhaps as a footnote, or perhaps a useful way of signposting what they're doing in some shorthand fashion.
As I said in my reply, D&D began as a game about making stuff up: worlds, characters, monsters, the events that occur to them, the places where those events happen, the tools (spells, magic items) that are used in undertaking those events. This an idea of lore and canon as being in the service of that creative purpose, and not ends in themselves.
And any suggestion that someone who takes that view has no principled basis for meaningfully classifying one game as D&D and another as (by way of contrast) DitV, is just silly. Back when that view was the (almost unrivalled) norm - say, the first decade from 1974 to when campaign setting really started to become mainstream, the DL modules were coming out, etc - people could still distinguish between different genres of RPGing, different mechanical systems, etc.
So you didn't consider your BW game set in Greyhawk playing D&D... right?
I don't think of it as D&D, no. But I think of it as a GH game.
But that doesn't follow merely from what I said; it's an independent judgement. I said,
At a minimum D&D includes playing the game that Gyagx and Arneson wrote. That doesn't mean I think that D&D
entails , or has as a necesary condition, playing the game that Gygax and Arneson wrote; but it does mean that I think if you're playing the game that Gygax and Arneson wrote, then that is a sufficient condition for playing D&D.
I made the point because it seemed to me that [MENTION=7635]Remathilis[/MENTION], by insisting that all discussion must begin from "canon" - which, in practice, seems to mean FR + "the multiverse" but not a multiverse that includes peoples homebrews - seemed to be implying that playing the game that Gygax and Arneson wrote, by making your own stuff up and picking and choosing as seems like fun, is not a paradigm instance of playing D&D.