By Costikyan's definition, a collective storytelling thingy where players make decisions as characters (their "tokens") to try and achieve the goals of said characters, managing the resources (abstract and concrete) those characters have, is "a game". That there is no winning condition is not an issue to him as such.
A definition that broad could just as easily cover real life as well.
I'm inclined to define "game" more narrowly, particularly in a way that there be clear conditions for winning and losing. When those conditions are highly flexible or open to interpretation (to the point of even being completely subjective), I don't consider the activity a game any longer. It becomes an exercise or a fantasy. Thanks for helping me place my opinion in perspective. I will check out that essay.
[spoiler]* Ken rolls to kick Senn in the nuts!
[/spoiler]
Well, the problem with this topic is (as with pretty much every topic ever debated on Backstage, so has it been, so shall it always be, for ever and ever amen) we can't just draw an arbitrary line between our two options. I mean, charades is fairly open to interpretation, although I suppose the basic rules aren't. But again, even in RP there is a "skeleton" of rules, however vague they might be. Still, that doesn't really defeat your submission of anything open to interpretation not being a game, nor does it refute the fact that people trying to "win" at RP ruin it for everyone.
So, I guess this might be considered a moot point. Whether or not you consider RP to be a game of any variety, stomping on everyone else's sandcastle so you can be the hero is the fast track to a collective kick in the teeth from the rest of the community you'll alienate in the process.
[spoiler] You have activated a spike trap. Roll your save against DC 34 or take 2d10+5 damage. [/spoiler]