Just what is a role-playing game? In particular, Dungeons & Dragons and other fantasy role playing games can be summarized with some of the words of Gary Gygax from the 1978 Advanced Dungeons & Dragons Players Handbook.
"Swords & sorcery best describes what this game is all about, for those are the two key fantasy ingredients. Advanced Dungeons & Dragons is a fantasy game of role playing which relies upon the imagination of the participants, for it is certainly make-believe, yet it is so interesting, so challenging, so mind-unleashing that it comes near reality."
"The game is ideally for three or more adult players; one player must serve as the Dungeon Master (or Game Master-DM or GM for short), the shaper of the fantasy milieu, the 'world' in which all the action will take place. The other participants become adventurers by creating characters (and verbally acting them out) to explore the fantastic world and face all of its challenges -- monsters, magic, and unnamed menaces." "Imagination intelligence, problem solving ability, and memory are all continually exercised by participants in the game."
"You interact with your fellow role players, not as Jim and Bob and Mary who work at the office together, but as Falstaff the fighter, Angore the cleric, and Filmar, the mistress of magic! The Dungeon Master will act the parts of 'everyone else', and will present to you a variety of new characters to talk with, drink with, gamble with, adventure with, and often fight with!"
"As with most other role playing games, this one is not just a single experience contest. it is an ongoing campaign, with each playing session related to the next by results and participant characters who go from episode to episode." "Thus Advanced Dungeons & Dragons is, as are most role playing games, open-ended. There is no 'winner', no final objective, and the campaign grows and changes as it matures."