Role-playing game (RPG): A leisure group activity with the goal of collaborative invention and exploration of a shared fantasy world. It is structured by agreed-upon rules and procedures, with the most salient one being that most participants (players) embody a personified character within said fantasy (see Montola).
Game master (GM): A specialized player role in RPGs that is tasked with embodying not a single "player character" (PC), but a number of "non-player" ones (NPCs), as well as with tracking, updating, and revealing the overall state of shared fantasy world to other players. GMs are typically granted far-reaching discretionary powers over the game world, referred as GM fiat. Different games in this survey use many terms to refer to game masters, but for the sake of consistency, we will substitute all of them with simply "GM" in the following.
Framing: Gary Alan Fine had applied Erving Goffman's "frame analysis" to RPGs to describe how communication between their participants occurs on three distinct levels/frames: social (between people), gameplay (between players), and fiction (between characters), with participants continuously switching or "keying" between them in the course of a game session (pp. 186-204). This survey will focus on the gameplay frame, but we will also examine how it is keyed from the other two, as well. Gameplay and fiction frames are also referred as ludic (from Latin "ludus" – "game") and diegetic (from Greek "diegesis" – "narration"), respectively.
Social action: According to Max Weber, "an action is ‘social' if the acting individual takes account of the behavior of others and is thereby oriented in its course". Our primary interest here are persuasive social actions taking place in the fiction frame ("in-fiction") of RPGs, wherein the acting character attempts to influence the behavior, beliefs, or affective state of one or more others. In the following, we will refer to the former character as the social agent, and the latter as the social patient(s), or simply as "agent" and "patient". The players embodying them in the game will be referred as "agent player" and "patient player", respectively, even if one of them is the GM (who typically isn't referred as a "player" in RPGs).
Player agency: In RPGs, the ability of a player to make meaningful choices regarding their character and their in-fiction behavior. A player's agency can be invalidated if the gameplay systems allow the GM or another player to render their decisions regarding their own character meaningless, such as (hypothetically) using persuasive social actions in-fiction to make another's character behave in ways contrary to their player's intentions.
Stats: Short for "statistics". Numeric (typically expressed as short integers) representations of character qualities or, more specifically, their effectiveness at accomplishing certain in-fiction tasks. Primary stats are typically few in number and refer to natural aptitudes, such as strength and intelligence; while secondary stats are usually more numerous and refer to learned abilities, such as skills.
Relationship value: A type of stat representing some aspect of a relationship between two characters, such as how much they like or trust each other. Relationship values in RPGs are often asymmetric, meaning that each character has a separate relationship value for everyone else and two character's values are not necessarily equal, simulating unreciprocated feelings and attitudes.
Mechanic: In RPGs, a repeatable procedure that takes the players out of the fiction and into the gameplay frame, in order to resolve, i.e. to determine the outcome of, some in-fiction event according to previously agreed-upon rules.
Game system: A set of gameplay procedures used by players to negotiate and to agree upon what happens in their shared fantasy. According to a principle formulated by Vincent Baker and Emily Care Boss, "System (including but not limited to ‘the rules') is defined as the means by which the group agrees to imagined events during play."
Core mechanic: In RPGs, a gameplay mechanic that is used to resolve all player character action in-fiction in a unified manner unless a more specific procedure applies. In cybertextual terms (see Aarseth), the core mechanic in RPGs is a (usually probabilistic) transition function taking as input the agent's objective, the numeric stats of all characters involved (at minimum, the agent's), as well as other circumstantial in-fiction factors, and outputting the outcome of the agent's action on the gradient of success (at minimum, whether it succeeds or fails).
Gradient of success: A unified six-point scale of possible in-fiction outcomes of a player character's action, as described by Eddie Webb. The points on the scale are: No-And (the character fails to accomplish their objective, and their attempt has an undesirable side effect), No (the character simply fails), No-But (the character fails, but their attempt nonetheless has a beneficial side effect for them), Yes-But (the character succeeds, but with an undesirable side effect), Yes (the character succeeds), and Yes-And (the character succeeds with additional beneficial side effects).
Agent-patient configuration: A term used here to describe one of three possible agent-patient role distributions among player and non-player characters in social actions: "PC agent, NPC patient" (a.k.a. "player-versus-environment" or "PvE"), "NPC agent, PC patient" ("EvP"), and "PC agent, PC patient" ("player-versus-player", "PvP"). "NPC agent, NPC patient" is of little interest to this survey, since such social actions are typically left up to the GM fiat and unregulated by the rules.
Experience points (XP): Abstract tokens whose acquisition by a player character represents them learning from their experiences. Upon accumulating some number of XP, the character's stats improve or they gain new abilities.
Dice: Ubiquitous gaming aids used as randomness generators in RPGs. This survey uses the standard dice notation, where "dX" describes a single X-sided die (e.g. a cube-shaped "d6" or a twenty-sided "d20") while "NdX" means "roll N X-sided dice and add up the results".