What is a game? A page of definitions...

In the process of preparing for a lecture on game studies I remembered I had assembled these definitions for my research. Maybe they will come in handy for some else...

Johan Huizinga
A voluntary activity or occupation within certain fixed limits of time and place, according to rules freely accepted but absolutely binding, having its aim in itself and accompanied by a feeling of tension, joy and the consciousness that it is different from ordinary life.
(Huizinga 1938)

Roger Caillois
An activity that is free:  in which playing is not obligatory; Separate: circumscribed within limits of time and space, defined and fixed in advance.

Uncertain: the course of which cannot be determined, nor the result attained beforehand, and some latitude for innovations being left to the player’s initiative.

Unproductive: creating neither goods, nor wealth, nor new elements of any kind.

Governed by rules: under conventions that suspend ordinary laws and for the moment establish new legislation, which alone counts.

Make-believe: accompanied by a special awareness of a second reality or of a free unreality, as against real life.
(Caillois 1961)

Greg Costikyan
A game is a form of art in which participants; termed players, make decisions in order to manage resources through game tokens in the pursuit of a goal.
(Costikyan 1994)

Stephen Sniderman
A game is a play activity that consists of an object (a goal or goals that the players are trying to accomplish) and constraints on the players’ behavior (what they must do and/or what they may not do in attempting to achieve the game’s object).
(Sniderman 1999)

Bernard Suits
To play a game is to engage in activity directed towards bringing about a specific state of affairs , using only means permitted by rules, where the rules prohibit more efficient in favor of less efficient means, and where such rules are accepted just because they make possible such activity.
(1978 cited Juul 2003)

Elliott Avedon & Brian Sutton-Smith
At its most elementary level we can define game as an exercise of voluntary control systems in which there is an opposition between forces, confined by a procedure and rules in order to produce a disequilibria outcome.
(1971 cited Juul 2003)

Chris Crawford
Games are conflicts in which the players directly interact in such a way as to foil each other’s goals.
(Crawford 2003)

Katie Salen and Eric Zimmerman
A game is a system in which players engage in an artificial conflict, defined by rules that result in a quantifiable outcome.
(Salen & Zimmerman 2003)

Tracy Fullerton, Chris Swain & Steven Hoffman
A closed, formal system that engages players in structured conflict and resolves its uncertainty in an unequal outcome.
(Fullerton et al. 2004)

Isaac Barry
An object of rule-bound play.
(Barry 2005)

Jesper Juul
A rule based formal system; with variable and quantifiable outcomes; where different outcomes are assigned different values; where the player exerts effort in order to influence the outcome; the player feels emotionally attached to the outcome; and the consequence of the activity are optional and negotiable.
(Juul 2005)

Ernest Adams and Andrew Rollings
A game is a type of play activity, conducted in the context of a pretended reality, in which the participant(s) try to achieve at least one arbitrary, nontrivial goal by acting in accordance with the rules.
(Adams & Rollings 2006)

Jesse Schell
A game is a problem-solving activity, approached with a playful attitude.
(Schell 2008)