If you are familiar with the World of Darkness settings, all you need to know is that we use "Old" or "Classic" World of Darkness setting with the 20th Anniversary Edition rules where available. We support Vampire: The Masquerade (V20), Werewolf: The Apocalypse (W20), Mage the Ascension (M20), and Changeling: The Dreaming (C20). Gifted mortals are supported in the V20 supplement Hunters Hunted II, though may be subject to STer approval to ensure they fit into our setting. Rules from "New World of Darkness" or "Chronicles of Darkness" as it is now referred to, will not be adapted to our setting.
If you're not familiar with World of Darkness, that was probably all gibberish. Not to worry, we are very friendly to new players and will walk you through any rules you need to know. We will help you build the character you envision, and represent it as faithfully as possible in character sheet form.
World of Darkness was published by White Wolf back in 1991, and has since been picked up by Onyx Path. It is not a stand-alone game itself, but rather is the shared setting for each of their detailed single venue games (Vampire, Werewolf, Mage, etc). Each of the games use the Storyteller System for rule mechanics, which creates dice pools of d10s to resolve actions. Overall, the system was designed to support storytelling and character customization, so don't let the strange terms and stats intimidate you.