A role-playing game (RPG) is a type of game where players assume the roles of fictional characters via role-playing. In fact, many non-athletic games involve some aspect of role-playing; however, role-playing games tend to focus on this aspect of behaviour.
At their core, these games are a form of interactive and collaborative storytelling. Whereas cinema, novels and television shows are passive, role-playing games engage the participants actively, allowing them to simultaneously be audience, actor, and author. An example of this difference could be the classic scene in a horror film when a doomed character ventures alone into the basement to fix a broken fuse. The audience experiences dramatic irony and says, "Don't go down there!" because they know the monster is lying in wait. In a role-playing game, the player may choose what to do about the broken fuse.
In most role-playing games, participants play the parts of characters in an imaginary world that is organized, adjudicated, and sometimes created by a gamemaster (aka narrator, referee, dungeonmaster). The gamesmaster's role is twofold - s/he provides a world and cast of characters for the players to interact with (and adjudicates how these interactions proceed), but may also be respnosible for advancing some kind of storyline or plot, albeit one which is subject to the somewhat unpredictable behavior of the players.
Some newer role-playing games expand the players' powers beyond dictating the actions of their player characters. Some groups or games have rapidly rotating gamemaster duties, or in the more radical cases no gamemaster at all.
The cooperative aspect of role-playing games comes in two forms. The first is that the players are generally not competing against each other. Most sports, board games and card games place players in opposition, with the goal of coming out the winner. A role-playing game is not a zero-sum game; in the majority of these games, the only way to actually lose is not to enjoy the game. The second form of cooperation is that all of the players are writing the story together, as a team. At the end of a role-playing game session the events that transpired could be written into a book that would tell a story written by all of its participants.
Despite this generally non-competitive nature, RPGs usually have rules, which enable the players to determine the success or failure of their characters in their endeavors. Normally this will involve assigning certain abilities to each character - from something as mundane as being quite strong to having x-ray vision. Frequently dice are introduced in order bring in an element of chance, though this is not always the case.
Historically, role-playing games evolved from wargaming, but are generally simpler, more fantastic, and less realistic or historically exacting, and require far less space and equipment than the older and more traditional hobby.
The term "role-playing game" is used for a few distinct methods of play. The traditional method is a pen-and-paper or tabletop game played with dice by several people. These frequently use several types of polyhedral dice. Some games and gamers also use figurines on a grid (usually a square or hexagonal one) to depict strategic and tactical situations for play. This is especially used during combat which is often a significant aspect of such games. When figurines are used, then position, terrain, and other elements can affect the probabilities. (For example, a character making an attack from an opponent's rear or flank may gain a significant bonus on their chances "to hit" and may also gain advantages on any damage they inflict).
Sometimes figurines are not used at all, and sometimes a whiteboard, chalkboard or similar drawing surface is used in lieu of any figures or tokens. However, many gamers are also collectors of the figurines and engage in the related hobby of painting and customizing them.
Another mode of play is live action role-playing (LARP), in which the players physically act out their characters' actions. This type of gameplay is usually more focused on characterization and improvisational theatrics and less focused on combat and the fantastic, if only because of the physical limitations of the players themselves. Live action gamers often dress up as their characters and use appropriate props in the game. The related style of freeform role-playing is less physically oriented, and is often played at conventions.
The term is also used as a name for a genre of video games that almost always lack the "role-playing" element of pen-and-paper games but borrow many gameplay elements from said games. These games are called "computer role-playing games", or sometimes "console role-playing games" if one wishes to underline the distinction between role-playing games played on a personal computer and on a video game console.
These computerized simulations have become increasingly prominent over the last two decades. The most recent computer role-playing games have endeavored to incorporate social interaction via networking, beginning in the realm of text based chat rooms, and soon moving to static persistent worlds represented in the text MUD and the like (MUSHes, MOOs and MUXes). Currently, these have evolved to incorporate graphical representations of tokens (characters, equipment, monsters, etc.), as well as physical simulations obscuring much of the underlying rules of the games from users. Today, online role-playing games are defined by massively multiplayer online games such as Everquest and City of Heroes. These games (MMORPGs, or Massively Multiplayer Online Role-Playing Games) are played exclusively online and feature graphically intensive gameplay in a virtual world shared by thousands of other players simultaneously.