Marginal Utility (of a commodity)
[JV43] The maximum effort which a player will be willing to make – when behaving according to the customary criteria of rationality – in order to obtain a further unit of that commodity.

Metagaming
[JM99] Addressing the GM or other players as players to discuss aspects of the plot, character development etc. Usually done out of character. (Role Playing Games term)

Metaphor
[RD99] Correspondence of the Conceptual Map to Reality in an exercise (game).

Mode
[TR82] A design element of a computer game. A presentation to the user at one time (Same as a “move” in G-T)

Model
[TR82] A design element of a computer game. Elements of data that are used by engines. (See “Engine [TR82]” )

Move
[JV43] A component of the game. The occasion of a choice between various alternatives, to be made either by one of the players, or by some device subject to chance, under conditions prescribed by the rules of the game. Moves are of two kinds: personal move and chance move.

Multilogue
[RD74] Multiple, simultaneous dialogue organized by a pulse.