a game much like 'make-believe' or 'let's pretend' that you played when you were a child
a game where the players take on the roles of different characters within a fictional setting and go on adventures
an interactive story like a novel or a movie - except the actions of the players change the course of the adventure
a set of guidelines and rules that allow players to create interactive fantasy adventures powered by the joint creativity of all the players and the Realm Master
a type of game where players role-play by assuming the role of a character in a fictional world
a game in which players assume the parts of historic or fictional characters, and attempt to portray those characters' personalities achieve those characters' goals.
Lengthy, slow moving game with elaborate storylines that involve going on a quest and developing one or more characters on the way. Although traditionally turn-based, newer RPGs tend to incorporate real-time elements.
(also RPG) This takes a bit more to explain than I have room for here, so I'm just gonna point you back over to the RPG Concept section of the site.
This is a genre of game that has been around since the beginning of computer gaming. In these games, a player will use their character to defeat quests. These games are comparable to dungeons and dragons. All of the Final Fantasy games and Myst are examples of popular RPG games.
A role-playing game (RPG, often roleplaying game) is a type of game in which the participants assume the roles of fictional characters and collaboratively create or follow stories. Participants determine the actions of their characters based on their characterization, and the actions succeed or fail according to a formal system of rules and guidelines. Within the rules, players can improvise freely; their choices shape the direction and outcome of the games.