A functional definition, to begin: games are objects with which a subject interacts that interpolates her into the subject position of player.
This may be undertheorized, and I am not sure how comfortable I am with the word object, but it seems to me that it encompasses everything from a ball to a system of rules. And I hope to indicate by the use of "interpolate" that certain social systems are fundamentally implicated in the definition, and so to account for how in certain contexts a thing can go from being a game to not being a game, although nothing about the thing itself changes whatsoever.
The elephant, of course, is what the fuck is a player; the answer, of course, is the subject position occupied when the subject engages with a game. I am not entirely sure whether the tautology here is productive, or whether it is the critical flaw with my tentative definition. Or whether it is necessarily a (or this) tautology at all.
Some scattered notes, to continue: my functional definition is broad, but my interests are slim; video games (as a form) and Dungeons & Dragons, at least for now. The natural thrust will be to declaim things in a Theory of Everything idiom, but the work itself is always the particular & its labor.
I continue to assume that a systemic approach is key, with its foundation in the understanding of video games as rule-systems & the affective capacity of this sort of structure. I am beginning to understand that, however, the systemic is an approach that privileges the view of the developer over the view of the player, and that the production & consumption of video games is far more concentric in its form than, say, literature. Thus the player is as much a site of production (especially in tabletop RPGs, especially especially the figure of the DM) as the developer, and for the player the game presents (at least experientially) not a system but an ad hoc assemblage, with consistency/systematization taken for granted but never directly experienced. Which might be some sort of inadvertant commentary on how systems work, but whatever.
The difference, I think, is embodied in the Dungeon Master, who ostensibly occupies the role of the developer on a smaller scale, but who in practice tends (in my experience) to function as an assembler, tasked with giving the illusion of a mastery of the system that its both pointless and generally actively detrimental to actually possess. The DM, then, learns what rules she needs and improvises those she doesn't; and this is both at the level of "gameplay" and at the level of "narrative," (insofar as those can even be called different levels), given that the players have the capacity to (and often do) stray outside of the bounds of what has been planned. Which is all simply to say that if the assemblage experience is a byproduct of systems, it is also a mode of production in its own right, and the multiple sites of production that a game entails reflect this fact.
An example, based on some theory: if games can be said to have a grammar, then it follows that individual games fall within certain dialects. When someone familiar with syntax of gaming picks up a new game, they go through certain trials to determine which dialect it falls under; whether reading the manual, glancing at the configuration page, or loading the game and pressing buttons with an assumption of their effect, the goal is the same. This is precisely what I mean by an assemblage; the experience of a system of rules is not in place, only the response (or lack of response, and its relative adherence to expectations) to certain predefined actions. I rediscovered this recently on booting up Metal Gear Solid for the first time in many years; it took me over a full minute to navigate through the menu screens as I reflexively pressed X to accept, when it was actually the decline/back button. I played plenty of games with that system back when it was a current dialect, and knew it very intuitively back then, but I had forgotten it as it fell into disuse. So while I understood the grammar, the dialect had, through disuse, grown exceptionally rusty, on the verge of totally disintegrating, and it took almost as long to relearn it now as it did to internalize it then.
When I make the comparison to literature, I am not operating on the terms of active versus passive consumption, as the comparison is usually framed. All production is consumptive production, and all consumption is productive consumption; I take this as a given. Passivity is quite simply not an issue. The difference is that of the difference between the subject position "reader" and the subject position "player" -- subject positions which, it must be clarified, are not mutually exclusive and often overlap or intermingle. For the interpolated reader, the P-C loop remains closed, albeit variable in size, and, as I have tried to say, nonbinary; each incorporates its opposite, and the activity of consumption can prove very much more fruitful than the activity of production. On the other hand, the game tends more toward a P*-C structure, where consumptive production can be iterated. As I have said for D&D, this would look like two concentric circles, with the DM bridging the C of the outer circle (ie standing as consumer of the full product) and the P of the embedded circle (ie standing as thr producer of the sub-product).
We could take fanfiction, for instance, and apply these theories to it. We have to assume two distinct social contexts, wherein the fanfiction writer is first interpolated as reader, and second as player. Fanfiction, when interpolated as an activity of a reader -- whether by the author of the specific piece or its reader -- and therefore a function of the P-C loop, is a form in which the productive aspect of the productive consumption it represents is the "canon," as opposed to other aspects of the literary mode. That is to say, the nutritive aspect of the consumed fiction is the canon, and it is converted into the energy which has as its outlet the fanfiction. When the fanfiction is interpolated into the role of player, the author is implicated in a mode of production, treating the originating fiction as a whole as the resources that are consumed in transformation with labor in order to create a new product. So, roughly, "reading" fanfiction takes the form of "continued adventures," while "playing" fanfiction takes the form of something like slashfic.
Having assumed all of this, a position: the fundamental & unique aspect of gaming as a form is an affective node we can call "frustration." The linguistic metaphor, the economic metaphor, and the definition all bear this out; again, however, there is a disconnect between the systemic and the experiential. The experience depends on the activation of the node, and it branches out into at least two paths; "triumph" and "boredom." "Boredom" then branches further, although I'll not attempt to diagram this all here. Suffice to say, for now, perhaps, that the carnival game embodies these three nodes; in ring toss or guess the number of jelly beans in the jar or whatever, the player begins in frustration, and advances either to triumph or boredom, at which point the next game is begun. More complex games are those which track through boredom to various other affects, and in so doing provide the player with an experience which builds upon the unactivated affective positions through which they have passed so that the activated affect position is colored by them.