OSR gaming is not about nostalgia. It's not about playing an old rules set just because it was old. It's about updating or rediscovering a style of table top gaming that was left behind by mainstream game publishers, and evolving the style with the benefit of 30 years of experience.
You may have a different definition of OSR gaming. There are plenty of primitive screwheads arguing on message boards whether a game that drops clerics can still be considered an OSR game, for instance. What follows is my definition, and it explains much of the focus of my blog.
OSR Gaming: The role of the game master is to act as an impartial referee and present a pre-defined setting, while giving the players complete freedom to make their own choices within the setting. We shorthand it nowadays as "sandbox gaming". To me, it's that simple. OSR gaming requires giving the players the freedom to explore a setting, and using rules that facilitate exploration as the primary mode of play. Everything else is just details.
(I like the word "setting", but I wonder how many times "milieu" shows up in the 1E DMG?)
Building hex-crawls, site-based locations, random tables for content, those are all tools and techniques for defining the setting. Those are the kinds of things that are evolving by borrowing ideas from 30 years of game publishing. Those are the types of things that are maturing through the efforts of the DIY publishers and the talented bloggers out there.
What about the choice of rules? The simpler rules of early games make it a lot easier for a referee to create a sprawling setting for sandbox play than a heavy system - like those systems where a monster stat block takes paragraphs and pages. But folks have certainly tried to play modern rules-heavy games in the older style, and there are plenty of Pathfinder or GURPs bloggers in the OSR blogosphere taking part in the conversations.
Games like early Dungeons & Dragons, where an over-arching objective is to recover treasure and level up your character, provide a strong incentive to interact with the sandbox regardless of the setting details or story. But not all OSR games have a class and level system, either.
Conversely, just because a particular adventure or campaign uses an older rules set doesn't make it an OSR style game. Dragonlance was published for 1st Edition AD&D, but the plotted nature of those adventures, and the use of pre-made characters, takes those adventures completely out of the realm of player-driven sandbox play.
My pocket is still full of opinions, but alas, the rest will have to wait until tomorrow. I want to discuss some of the publishers doing DIY OSR games and why they get me all fired up with the sandbox joy.