So in yesterday's post I mostly talked a bit about why I like long term play and the effect that it has on a game, and in the process I mentioned this idea that such play is a cornerstone of old school and neo-classical gaming. I don't mean that it's not possible to have an neo-classical one-shot, but long term play supports a couple of features that make those kinds of play styles really different from more modern styles.
The main thing I want to focus on for now is that it allows the campaign's style to coalesce, in a really natural way, around player interests. You have time to explore things and try out different ideas; the story can develop from random chance, player decisions, and spur-of-the-moment DM inspiration rather than being pre-planned. And, in particular, this style of incremental campaign design allows players to discover what they like as they play. They don't have to understand their own preferences well enough to be able to explain them to the DM as she's planning the campaign.
None of this is unique to neo-classical modes of play, but that kind of organic, improvisational development is a key feature of the kinds of games I'd describe in that way.
Now, part of my reason for saying that is that OD&D and Basic D&D are very clearly built for long-term play. The XP/level system assumes you're going to be playing for at least a half-a-dozen or so levels. It takes a long time to get to those levels. So to a certain degree I'm working backwards here and trying to figure out why those features are in the game in the first place, but I've also seen the effects of assuming long term play for long enough now to know a few reasons why building a system this way would be a good idea.
But those mechanical features are important, and they bring me to the point I'm trying to make in all of this: The ability to support long term play is an important feature of a lot of what I'd call "neo-classical," and it has some pretty serious mechanical underpinnings. The entire XP system of OD&D, the part of the game that makes it tick, is built around this assumption of campaign length. The rate of leveling. The number of levels. The way the power level changes as a character gains XP.
Not all systems support long term, open ended play. If it has a level cap that your players are geared to hit within a year or two, that's not going to work. OD&D does have level caps, true, but at a normal rate of treasure gathering its going to take your characters three, four, or more years to start hitting those levels.
Furthermore, if the power level changes really dramatically over the course of a few months or a year, then the DM either has to accept that the threats she assembles have a strictly limited shelf life, or that she needs to be willing to make things the party doesn't explore immediately level up along with them, which can create more work and damage verisimilitude. There's not quite so much room to wander around and explore different options, because if you don't handle something fairly quickly once you become powerful enough for it, it quickly becomes irrelevant.
And in a really good, long term, neo-classical kind of game, the players are eventually going to find something they like to do better than leveling. A huge part of the kind of campaign I'm describing is that eventually the players are going to find something to do that basically ignores the rules, and at that point, leveling becomes a distraction. Even, perhaps, a nuisance. You can use this to your advantage ("Do you go for the gold and level, or work towards a less-lucrative but more personally fulfilling goal? Dilemma!") but I have a strong suspicion that the reason leveling in OD&D is so hellaciously slow (besides just making it "mean more" when you do finally level, and the general old school philosophy of driving the players crazy) is so you can use it as a motivator in the early stage of the game, and then ignore it most of the time after that.
If that's where the game goes. Which is, when you get down to it, what this kind of play is about.