Tony Vargas
Legend
You're unlikely to find a worse one, but, hey, it got a discussion started, didn't it?Maybe there's a better analogy?

(nothing leaves a thread at 0 replies like being all reasonable and non-controversial)
Still not see'n it as distinct to RPGs. A campaign is a series of sessions, sure. A night of poker is a series of hands. A chess tournament can be a series of instances of chess that goes on and on.I see RPG's as having three levels. At the top, you have the RPG itself which we use to build a campaign. At the next level, you have the campaign which, in my mind, is the game that this group is going to play, and at the third level, you have the session, which is roughly analogous to a single instance of the game.
For most games though, you only have two levels. The game and the instance. You don't use charades, to use the example, to build a specific kind of pantomime game that players then play. You just play instances of charades. There's no higher level tier, such as what you get with RPG's.
And, I run convention games a lot, they're typically a complete RPG in one session (instance).
I think the reason you see a hard-to-define difference between RPGs and other sorts of games, is that the formalized D&D-style approach to roleplaying as a cooperative game with rules & dice & such (as opposed to a game with costumes & happy endings), has only been around for 44 years, now, and has maybe undergone 15 years worth of development in that time, thanks to the persistent stagnation of the gateway to the hobby. There's a reason that having a GM seems like one of the big, obvious, distinction between TTRPGs and CRPGs/MMOs and non-RPGs: because a GM who overrides the rules as a matter of course (see other threads on 'fudging,' 'balance,' &c), is helpful when the rules are lacking, and the more the rules lack, the more necessary the GM.
Can anyone think of an RPG where the GM seems almost superfluous?
TL/DR: RPGs don't seem like games, because they're such bad games they're barely recognizable as such.
There. 'Cynical bitter old man' rep secured...