World of Darkness is divided into many sub-games with very different rules, rather than unified rules like The Everlasting, WitchCraft, or really any other roleplaying game ever made. World of Darkness is unique in that it has dozens of different sub-systems to handle the same thing.
Unified rules are vastly overrated.
The best RPGs have systems built to reinforce their settings; ex. WEG Star Wars, D&D, Vampire. The worst are the ones where the mechanics are completely misaligned with the setting; ex. d20 Star Wars or any of the countless d20 settings where the setting fought with 3e D&Ds basic assumptions of level-based advancement, magical healing and armor as your primary defense.
Frankly, kitchen sink urban fantasy is rather rare. Far more common to the genre is a focus on a particular type of supernatural, possibly with a token teammate that is another type (the most common seeming to be a token werewolf ally in a vampire story where the werewolves are traditionally the enemies of vampires).
Also common is a "conservation of detail" origin for all the supernatural elements of the setting; ex. the shared ancestor of the vampires and lycans in Underworld, everything being a demon of some kind in the Buffyverss, Vampire Diaries/Originals vampires and werewolves both being the result of witch's spells/curses, or all the supernaturals in Lost Girl being Fae.
Each of the main WoD game lines is self-contained to focus on particular themes. The Biblical origins of vampires fits perfectly with its themes of guilt/sin and holding onto your humanity in the face of a monster within you struggle to control. The consensus reality with magic as willworking supports what I call "the dark fantastic" themes of magic being both dangerous and wondrous.
The themes of Vampire would be lost if they're not suffering God's curse, but are actually thaumivores resulting from Caine's long ago botched Awakening. The themes of Mage would be lost if the Biblical God were real and therefore every form of magic outside of Christian miracle workers and the natural magics (precursors of the natural sciences) are actually the work of infernal powers.
Neither of those play well with "lets roll massive piles of dice as we play Captain Planet furries in a doomed war against the love-children of Geiger and Lovecraft."
Allowing each to focus on its respective strengths both thematically and mechanically instead of getting lost in a bland stew of a fantasy kitchen sink is a big part of why nothing has managed to eclipse WWs settings; they're evocative in ways more universal settings can never be because they're a ready to play world with distinctive archetypes, not a toolkit filled with generic examples.
- World of Darkness is really bad at playing together with multiple different splat types due to incoherent world building and unbalanced rules.
You call this a bug; I call it a feature.
D&D also sucks at having multiple different monster PCs in the same party. There's a reason you're typically limited to humans/near humans of approximately the sams level of ability. Try writing an adventure for a party consisting of a human fighter, a lich, a gold dragon, a balor and a medusa.
By creating the game lines as separate entities, you're limiting your pallet just as D&D limits you to humans, elves, dwarves and similar.
That said, the system is eminently hackable. For a Mage/Vampire crossover we made only direct sunlight do damage to vampires and removed the "must sleep during the day/limited daytime dice pools" entirely.
- The metaplot is overbearing in the extreme, and there's no option to ignore it or remix it.
No, the metaplot is entirely ignorable... or I would have had to end my Mage game in 2004 when the metaplot said the world ended. Also, if it was overbearing and unable to be ignored I would have had to include the Avatar Storm in my games instead of ignoring it entirely for years until playing up the Storm's end was a useful plothook for a new campaign.
When I was ready I also managed to mix Gehenna, the Apocalypse and Armageddon into a single narrative where the PC mages managed to stop the whole thing and turn the wheel towards and upwards trajectory where, though still dark, there is now hope for a better tomorrow if you're willing to work for it.
I've been playing a post-Gehenna/Apocalypse/Armageddon setting for 13 years now with all manner of interesting developments (ironically, I'd introduced the concept of a "Spirit Technocracy" made up the disembodied masters about 5 years before the revised Void Engineer convention book introduced them. Mine though were seeking to regain control over the Technocrats on Earth once the storm died down... resulting in a permanent schism with a Technocratic faction semi-allied with the Traditions and another who'd been completely subsumed by the spirits until they were little more than drones).
So this claim is just flat out wrong.
- Aside from a few obscure mentions in supplementary books, there isn't a plethora of campaign worlds to play with like there is in, say, D&D or Rifts.
Do there need to be? Again, taken at face value, there's the Vampire campaign world, the Werewolf campaign world, the Mage campaign world, the Wraith campaign world, Changeling, Hunter, Demon and Orpheus campaign worlds. Each presented its own supernatural type as preeminent with the others defined in relation to it.
Gaia and the Triat are not the supreme spirits of the Vampire setting... if they exist at all they're demons who once masqueraded as the pagan gods.
Calling them all a single setting is like saying Forgotten Realms, Eberron and Nentir Vale are all the same setting because all of them have humans, elves, orcs, dragons, clerics, fighters, rogues and wizards.
- The setting is arbitrary and doesn't really let you change it up. For example, ghost PCs only exist in World of Darkness and not Chronicles of Darkness unless you homebrew it, and demon PCs are tied to Christianity or to the God-Machine rather than something more open-ended like Vigil or Lost.
Clerics being the only ones with healing magic and all arcane magic being Vancian is equally arbitrary and the system fights you if you try to change it. What's your point?
OWoD also had plenty of different types of demons... each specific to their settings.
Demons in Vampire are tied to Christianity because the whole SETTING is tied to a Christian mythos.
In Werewolf the demons are lovecraftian horrors born of the personification of entropy itelf.
In Mage they're entities from the Astral umbra, the embodiments of mankind's beliefs about demons.
In Demon they're again Christian-themes because Paradise Lost featuring Lucifer as the protagonist is perhaps the most iconic depiction of sympathetic demons in Western culture. The other biggie is Dante's Inferno which also depicts specifically Christian demons.
- The fandom is cultish. For example, when Mage: The Ascension 3rd edition came out in 2000, lead developer Jess Henig received hundreds of death threats by email and was terrified to open his inbox for years. (The cult of fandom is part of the reason why I suggested making a new game entirely rather than trying to hack the X of Darkness rules. I specifically want to avoid attracting cultists.)
All fandoms are cultish. Or was D&D 4E embraces by one and all with open arms and no threats whatsoever made against the developers of that edition?
Mage Revised was basically the same thing as 4E D&D... a radical change from previous editions that attempted to for a "One True Way" that was meant to bring the game into line with the bleak hopelessness of the other WoD settings; cutting off the fantastic elements of the spirit world, turned Avatars into symbiotic organisms that humans merely hosted, introducing the concept that magic was dying and then adding the never before even hinted at End Times called Armageddon (so it would line up with Gehenna and Apocalypse) that they claimed had always been on the horizon.
There's a reason he wasn't asked to return to do the 20th Anniversary Edition of Mage. His changes to the setting were an absolute misread of what the customers enjoyed about it; namely that it was NOT like all the other WoD settings.
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What your main beef could be summed up as is; "it's not a toolkit."
You clearly enjoy tinkering with rules, but you seem blind to the fact that not everyone does.
Not everyone wants to build a motorcycle from scratch. They're not interested in how you could customize it to be the perfect ride for them... they just want a bike that runs so they can take it out and enjoy the sun, fresh air and countryside.
Your complaint is that the WoD only sells fully assembled motorcycles and not boxes of parts you have to assemble yourself.