It['s] fun to play around with a system [that] has the elements of GURPS I like (skills, detailed combat, etc) but feels closer to the roots of the hobby (random rolls, death looms, etc).Rob's inclusion of random rolls among "the roots of the hobby" triggered a realization in my mind: all other issues aside, what I really most enjoy about old school games is their implicit recognition of the fact that the referee is a player too.
Let me explain. Much as I enjoy mechanically simple games, mechanical simplicity isn't necessarily a make or break thing for me when it comes to enjoying a game. Certainly I have a lot less tolerance for complex games than I used to, but I wouldn't reject a mechanically complex game out of hand, if I felt that complexity gave me something I couldn't get through simpler rules. And the main something that could grab my interest these days is, for want of a better word, surprise.
As I see it, a good part of the enjoyment in being a player in a RPG campaign stems from ignorance. You don't know the details of the adventures the referee has planned; you may not even know much about the wider setting in which those adventures are based. In many old school games, you don't even know what sort of character you'll be playing until you roll some dice and see. Over time and through play, all these instances of ignorance are lessened to some degree and the process of doing so leads to much fun.
The referee isn't quite so lucky. He creates the campaign setting and adventures set therein. He's by nature a keeper of secrets and so possesses something akin to omniscience -- at least from the players' point of view. Consequently, the scope for his being surprised is much more limited. It's always there, of course, because it's impossible to predict what players will do, but, even then, there are (generally) limits to the unexpected mayhem they can wreak. After all, the referee establishes most of the conditions under which the players make their decisions in the first place and so already has a leg up on planning to deal with consequences.
That's why, these days, I like games with a lot of randomness -- the baleful "swinginess" that so many modern game designs are trying to eliminate as "un-fun." Such randomness may be irksome to players, but it's essential in my opinion for the enjoyment of referees, as it presents a factor that's wholly out of their control. This is also why I also shy away from "story" in adventures, preferring instead something much looser. As a referee, I often find it frustrating enough knowing all the details of a dungeon level beforehand, but throw in a plot with pre-determined scenes or events and I start to feel as I'm not playing a game anymore, or at least not the same game as my players.
Perhaps I'm not. Perhaps one of the trade-offs in being a referee is you don't get the chance to be as surprised as the rest of the players. I'm not convinced that's true, though. My Dwimmermount campaign has gone off in a number of directions I didn't expect and all because I purposefully limited my "omniscience" and allowed the campaign to take on a life of its own, where random rolls and on-the-spot decisions in response to them played as big a role as careful forethought on my part. The result has been, in all honesty, one of the most enjoyable RPG campaigns I've ever run and the first in a long time where I've felt that, as referee, I was every bit as much of a player as the rest of the people sitting round my dining room table.
I certainly wouldn't claim that any of this stuff is inherent to old school play. After all, I've played in plenty of campaigns where this wasn't the case. Likewise, I don't think more modern game designs make it impossible to run a campaign like the one I'm running right now. However, I do think that older designs make it much easier to do so, as they were created in an environment in which "gamey-ness" -- such as randomness and player skill in responding to it -- was a given rather than merely one option among many. These are games from a "pre-theoretical" world, when designers still largely saw RPGs as contiguous with their precursors rather than divergent from them, if that makes sense.
This has turned into something a fair bit more rambling and incoherent a post than I'd intended but that's the nature of thinking out loud, I suppose. I guess all I'm really saying is that I like playing games whose mechanical underpinnings afford the referee a greater scope to be a player of the game rather than its "master" (never mind "storyteller," "narrator," or anything of that sort). I think the shift away from that, which you can see even in late OD&D, is one I don't find especially congenial and that I've happily cast off over the last year and a bit. Thank goodness.