Immersive Stance
[JM99] Also called "Deep In-Character Stance", although this is controversial. Mode of play in which player closely identifies with their character, feeling what they feel, often describing the sensation as "channelling" their character. (Role Playing Games term)

Imposition (upon others)
[RB99] A motivation factor or aspect of enjoyment in participation in MUDs. Players use the tools provided by the game to cause distress to (or, in rare circumstances, to help) other players. Where permitted, this usually involves acquiring some weapon and applying it enthusiastically to the persona of another player in the game world. Also see Achievement, Exploration and Socializing as alternative motivators.

Imputation
[JV43] The net potential set of results of a game play, esp. in terms of total payment.

Indirect
[CC82] The relationship property between two players wherein they interact through some third party or element of the game model. This feature is an aspect of triangularity of “Triangular [CC82].” See “Symmetric [CC82]”, “Asymmetric [CC82]” and “Triangular [CC82]”

Information (player’s state of information)
[JV43] The information a player has at the point of deciding on any given personal move’s choice.

Initial Inertia
[RD74] The initial difficulty in getting players involved in a game.

Interaction
[CC82] A basic, necessary and fundament property of a game (model) that differentiates a game from a puzzle or other passive acceptance of information. Interaction is the ability of the player to active one or more choices at each move. Interaction is critical to the successful reception of a game by players. (Also see “Representation”, “Closed”, “Conflict” and “Safety”)

In-Character Stance
[JM99] Mode of play in which player makes all decisions from their character's point of view. (Role Playing Games term)