About Dungeons & Dragons
Contrary to assorted modern folklore, Dungeons & Dragons -- also referred to as D&D or AD&D (the A stood for "Advanced", a modifier dropped from newer editions of the rules) -- is not a recruiting tool for demon-worshippers or an insidious method of mind control. It and other fantasy role-playing games (RPGs) are, in essence, advanced forms of the "cowboys and Indians" or "cops and robbers" play common to American childhood prior to the television era. What our parents accomplished solely by means of imagination, D&D players accomplish with imagination, pencil and paper, and a large bag of funny-looking dice.
Some of the subsequent variations do tend to the exotic, notably the Vampire: the Masquerade variants that involve live-action role playing (LARP). Note, though, that even the LARP games are just that. You may have seen tabloid-TV reports about so-called "vampire subculture", which is something else again. It's easy to confuse people who play vampire RPGs with people who think they're vampires (yes, there are a few of these, and I consider them Very Weird People), but the two groups seem to intersect very little. Both groups also overlap to a degree with the Goth subculture -- the fashion senses are similar, tending strongly to black clothing and stark facial makeup. But like the LARP gamers, Goths (not to be confused with the historical ethnic group) are mostly harmless if left to their own devices.
Drama & Mathematics
But we digress. The Dungeons & Dragons rules, originally published in the mid-1970s, were the first successful attempt to codify "cowboys and Indians" play into a formal system built around pencil-and-paper maps, preplanned adventures, and personalities represented in game terms by a series of numerical ability scores for such characteristics as Strength, Dexterity, and Wisdom. The choice of genre -- heroic fantasy -- came about because the designers were spinning the system off from rules built for boxed war games featuring cardboard counters or toy soldiers, and the variant from which D&D sprung was a medieval-warfare simulation.
Rather to the designers' surprise, D&D was a significant commercial success, and its publishers went on to become the founding fathers of a good-sized cottage industry. A number of RPG companies rose and fell over the next decade or two, publishing games set in worlds inspired by superhero comics, vast interstellar SF sagas, the old West, the post-nuclear future, gangland Chicago, and James Bond's brand of spycraft. None, though, quite caught the imagination or enjoyed the success of the original invention -- until someone thought to design an RPG in which the players took the roles of vampires. Vampire: the Masquerade caught the imaginations of Anne Rice fans and independent-minded teenagers alike, emphasizing role-playing and character development over "hack-and-slash" dungeon crawls. Though originally a living-room game like D&D, the character-driven system eventually spawned variant rules designed to facilitate live-action play, and LARP groups began to spring up in earnest.
The foregoing is, of course, highly condensed -- and somewhat dated now. While RPGs are still around, they've largely moved online (that market's 800-pound gorilla being World of Warcraft), and been supplanted in living rooms and game shops by collectible trading-card games (Pokemon, Yu-Gi-Oh, Magic: the Gathering, etc.) For more information about the games, start with the following sites:
Dungeons & Dragons.
(the official site for the pencil-&-paper game)
White Wolf Publishing
(publishers of Vampire: the Masquerade and related materials)