Why isn't my vamp/ "furry"/ slayer/ elf/ wizard/ whatever character accepted here?

You've got character types like that in the rules - I want to play my character here!

Quite simply, the reason you "can't" just bring a particular character from Ayenee into is that it most likely doesn't have a sheet, and is entirely likely to be a character type that isn't found in the World of Darkness. If you don't know what types are allowed, the "what is WoD?" page goes into detail about the game systems that WoD role-playing uses as a model for the characters allowed. People are sticklers about others having sheets, particularly if they have any sort of special abilities at all, and thus are very prone to jump down the throat of others who wander in, looking for role-play but unwilling to play by the rules that everyone who's already there plays by, enjoys, and make WoD a unique setting.

As for the character types that superficially resemble some things found in WoD, I'll handle a few of those in particular, explaining why they just don't fit.

Furries - while a crinos garou can possibly look very much like a wolf "furry" there's a reason furries as they're known in Ayenee don't exist in WoD. All the supernaturals hide that they are supernaturals from the normal population. While I or anyone who knows about the setting and the various powers of the various "splats" (supernatural character types) could come up with a reason for someone coming to look like a "furry" in pretty well each and every game system that does not mean that someone can wander into a WoD room with a "furry" who has no character sheet (hell, even if they DO have one), walk into a bar, and get served without causing a stir. One that was created by a vampire would be considered a walking breach of the masquerade, and subject to being hunted down and killed. One created by mages would be undone by Paradox after a short while as their body quite literally fell apart. A crinos were-creature causes delerium in normal humans, either turning them into gibbering fetal balls, or making them run in terror. Makes getting a drink damn hard. A fae "furry" just would not be seen by the banal populace, because they'd be disbelieved right out of existence. And so on, and so forth. Furries are damn cool - but they do not suit the setting of WoD, at all.

Vampires: regular, half bloods, daywalkers, and all their relatives - There are specific rules in WoD for vampires, and they're very specific about weaknesses and strengths and powers. If your character has a power that isn't in the books, or even if you have one that's similar, but doesn't use the same rules, then sooner or later you'll run into a rules lawyer (or rules Nazi, who are much worse) who will take issue with those powers. There's an incredibly vast range of powers (called Disciplines) available - but if you aren't familiar enough with the rules to explain why your character can fly, people are going to give you trouble.
What's that you say? Daywalkers? ummm - no. There's some vampire-associates that drink blood and are active during the day - but they're not vampires themselves. Vampirism is an all-or-nothing kind of thing. There's a couple of character types that violate that rule - but unless you have the books and make a character sheet by the rules (Yes, I'm harping on the rules - but guess what - we who play WoD like our rules. Don't take them away from us, they give our pointless rp lives meaning *grin*) then you'll get laughed at very fast.
What's that you say? your character's mother was bitten while pregnant with the character, so you get the advantages of being a vampire without the disadvantages? Umm... there's a technical term for what happens to the unborn child of a mother who's embraced. Its called "death". No ifs, no ands, no buts. While I'm on the topic, no, regular vampires cannot get pregnant and have children in WoD. There's a few who can - they're called "thin bloods" for a reason, and it's not a good one. Now, if you really want to play a character who has all the disadvantages of a vampire, without access to anything resembling the strengths of the vampires of WoD, then by all means, go ahead, make a sheet, and play a character who's considered a harbinger of the end of the world for the vampires. Oh, didn't I mention that? The thin bloods are considered a sign of the "beginning of the end" for vampires, and thus more hard-line-conservative types amongst vampire kind tend to hunt them down and slaughter them out of hand.
There are no hereditary vampires in WoD, you have to be turned into one, even if you're made by Kindred of the East rules. (side note - there is a whole different type of vampire, from the Kindred of the East rules, who are not bitten-and-transformed - they're closer to being ghosts with bodies, because they die with "Unfinished business" and unbalanced souls. There is a lot of variety in WoD - but we only accept the characters within the specific rules that are set out)

Slayers and other hunters: Monster hunters in general are allowed - if they're of the specific types we have rules for. What we don't have rules for in general are the ones like Blade, or Buffy. (Already sorta covered Blade-like vamp/human hybrids in Vampires, up above) Buffy's cool, the show is good - but the character itself doesn't exist by our rules. If you want a hunter type character, there's a few routes you can go. One is normal human, without any sort of supernatural powers at all - just weapons and quick reflexes. Another is the hunters from the book Hunter: the Reckoning, who are very close to normal humans - they just have a few minor abilities (some of which are called "edges") that allow them to hold their own against the supernaturals. No, not all humans are automatically imbued, nor are the Imbued gifted with madd powerz that you make up on the spot. There's some abilities they have - and quite a few they just wish they had...
There's a few others from different books, for instance the Asian "Shih" who hunt "demons" - but they're rare, and making them without having the appropriate book is rather foolish. You can do it - but if you do a specialized character without having the books you're likely in for getting nailed by someone who does have and know the books - and you won't last long.

I can go on and on, and probably will add to this page as people argue specific examples with me - but for now, I hope this works, simply to give you all examples of how Ayenee characters and WoD ones don't necessarily mesh, though they might superficially resemble each other. If anyone has problems with this page (I did try to be polite-but-honest, I swear) then email me at world0fdarkness@yahoo.com and I'll do my best to either clarify or correct the page.