A role playing game (RPG) is a broad family of games in which players assume the roles of characters in a fictional setting. Players take responsibility for acting out these roles within a narrative, either through literal acting, or through a process of structured decision-making or character development. Actions taken within the game succeed or fail according to a formal system of rules and guidelines. The original form, sometimes called the pen-and-paper RPG, is conducted through speech, whereas in live action role playing games (LARP) players physically perform their characters' actions. In both of these forms, an arranger called a game or dungeon master (GM/DM) usually decides on the rules and setting to be used and acts as referee, while each other player plays the role of a single character. Several varieties of RPG also exist in electronic forms, including multi-player text-based MUDs and their graphics-based successors, massively multiplayer online role playing games (MMORPGs) and also several Flash based Role Playing Games. role playing games also include single-player offline role playing video games in which players control a character or team who undertake quests, and whose capabilities advance using statistical mechanics. These games often share settings and rules with pen-and-paper RPGs, but emphasize character advancement more than collaborative storytelling.