Inspired by a conversation with my friend James at Recess...
I consider this an essential feature of any role-playing game text - if it doesn't have it, I'm not too interested in trying it out and I definitely don't want to spend money on it:
Clear delineation of the procedures of play.
I don't care what the game does - like, maybe it turns out I won't like what the game does: regardless, I'm perfectly happy to find that out if the text is clear about what I'm supposed to be doing to make it work.
I want to know what I'm supposed to be doing at each "scale" the game operates on. That is, what does the game look like and what are we supposed to be doing...
...as a whole?
It should answer questions like...
...how do we move from scene-to-scene?
...how do we know when to roll dice/draw cards/make use of mechanics?
...what parts of the big picture do we need to keep track of?
...how do we start a session of play?
...if there are different roles for the players (i.e. someone has to be "the Gamemaster"), what are the responsibilities associated with each role?
...what kind of preparation is necessary before starting?
...what kind of preparation is necessary in between sessions?
Most of the games I played and read back in the day, would end up clearly answering one or two of the questions, but would be vague about or oblivious to the other questions.
There's still a continuum here. Some examples:
Trollbabe, Dogs in the Vineyard (inspired by Trollbabe), Burning Empires, and Prime Time Adventures are all really clear: there's a section in each that lays out what you're meant to be doing at any given time; the different responsibilities for the GM and Players are clearly differentiated; there's a clear procedure for setting up the "scenario" for a session of play; there are clear rules for what to do in between sessions. There are still some holes (Dogs, for instance, doesn't tell you how you should start scenes), but, for the most part, these games have extremely clearly laid out procedures.
Note: this isn't a question about "lots of rules" or "a couple of rules" (i.e., "rules heavy" vs. "rules light"). Trollbabe has significantly fewer rules than Burning Empires, but it has an equally strong structure and equally clearly laid out procedures.
Some games do a good job answering a few of the questions, but are unhelpful about others. D&D 3rd edition is like this: on a moment-to-moment basis, things are pretty nicely laid out and there's a clear procedure for building encounters. But scene-to-scene or session-to-session, the procedures are extremely vague and "hand wave-y". You're supposed to "fill in the blanks", as it were, with your previous experience of playing RPGs.
Some games answer all the questions, but they aren't quite explicit about it or they purposefully leave certain parts of the procedure open to interpretation. Jared Sorenson's Lacuna is like this, as is, to a lesser degree, The Shadow of Yesterday.*
Anyway, that's the main thing I'm looking for now in RPGs: clear procedures. And, as a potential consumer, that's what I want to know about the game: does it have them? For instance, on this thread people are saying some nice things about Reign, but no one has said anything about how you're actually supposed to play. I mean, I'm assuming its supposed to work "like most other RPGs", which is kind of a bummer, because, IME, without clear procedures, actually attaining satisfying play is a pretty chancy proposition.
Hey - most of the games I play come out of the Forge (like Trollbabe) or were designed along some similar lines of thinking (Burning Wheel). The major thing that makes me like to play these games over "the games of my youth" (or the contemporary games that are following in that tradition) is that they have clear procedures! Now, it might be related that these games also tend to be "story-games" (i.e., mostly concerned with collaborative story-making), I don't know! What I do know is that I would gladly play a traditional-style RPG if it came with clear procedures for how it was supposed to work.**
*In TSOY there are procedures for moment-to-moment play and good advice about how to set up scenarios, but a lot of the answers to the other questions are "hidden" in the game's system of "Keys ". That is, once you figure out how to use Keys, the answers to the questions become apparent. I think TSOY is a really neat game, but after playing Trollbabe and Prime Time Adventures, it was a little frustrating to have to muddle through a session to figure this out.
**So, technically, because I've seen Burning Wheel, say, work, I could take some of the techniques from that game and apply them to a traditional game to get a complete, clear play experience. However, I guess I'd mostly prefer to play a game that was designed, from the ground up, with an overall procedure in mind.