The OSR movement has two camps. The Original camp which takes its rules structure from the original Dungeons and Dragons of 1974, and the d20 camp which came after. Any reliance on the OGL by the Original camp is due simply to the fact that they must for purposes of copyright. The boundaries of the Original camp is set by the early exposition of the official TSR rules. and the OSR usually tries to create as accurately as possible the rule structure of the actual rules published by TSR. The delineation of the Original camp is something like what follows:
The Original Camp
Original Dungeons & Dragons: Swords and Wizardry
Advanced Dungeons & Dragons (1e): OSRIC
Advanced Dungeons & Dragons (2e):
Holmes/Basic/Expert/Companion/Master/Immortal/Rules Cyclopedia: Dark Dungeons
The d20 Camp
d20 and variants
Dungeons & Dragons 3e/3.5
Basic Fantasy Role Playing Games
Castles & Crusades
Dungeons & Dragons 4e
Not a complete list, but you get the idea. And the reason for setting them up this way is delineate a difference in design from the two camps. The d20 camp relies heavily on the d20 system for game structure. While not necessarily rules lite they favor a single mechanic to govern most play and a universalism over specific technical rules. This concept has developed since WoTC took over D&D and has infiltrated the OSR.
While on the surface this is not a "bad" thing it has done something unpleasant to the tone of OSR playing. The idea that OSR implies rules light roleplaying. This is a basic flaw in thinking. Sure the Original edition was rules light in the sense that there weren't many rules, but rules light wasn't the "goal" of those early editions. And yes, the Original edition supported a certain type of play that was fast and lose exactly because there were not rules to cover every situation. But as anyone who has played Oe or S&W knows you _will_ be house ruling _lots_.
And that is the Advanced edition's logic. Gary realized that the early game was "barely there". Oe was a quick attempt to get the rules out there and sell them. 1e was Gary's attempt to implement fixes for the "holes" in the rules; to expand and unify the game into a more cohesive and complete whole. Some have called 1e Gary's house rules, and that may in a sense be true--but they were more than that. Though lots of house rules were play tested at early TSR, the ones that made it into 1e were the ones that early play testers felt contributed to play. There was no attempt to unify the game under a single mechanic. In fact I think we are naive if we think such discussions were not held at Gary's design meetings. Why not implement something like THAC0? These ideas were early on debated and discussed, but they didn't make the cut. Unified mechanics were nor a part of the game. And Gary made it clear that you start screwing with the structure of the system you will change the game.
By 2e Gary was largely out of the picture, and the game took a direction he was not entirely pleased with. And it's true 2e played a little differently from 1e. In my experience proficiencies changed the landscape of play more than any other single mechanic. And Gary himself made it clear he wasn't entirely pleased with the way they played in the game as is. He was in favor of a greatly revamped skill system that he only had the chance to envision once he put out LA. He also made it clear, however, that LA was not the lost 2e Gary would have created. By then he had been forced to move beyond D&D and his focus and effort where elsewhere.
That in my opinion is where Hackmaster tried to step in and save the day. Initially commissioned as a parody of the game to fill the demand of the readers of KODT, the design team quickly realized they had a golden opportunity. They could create a game that was the real deal while also preserving the spirit that permeated KODT. And that spirit was born out of the early days of TSR, the ones I mentioned in the last blog post. What they managed to achieve was to design a game that cut the difference between 1e and 2e and cemented the "feel" of those early days that is so well illustrated in KODT.
Whether Kenzerco realized it or not D&D was on the way to a monumental change in the late '90s that would divide the game into two distinct camps. The takeover by WoTC shifted the game to something different entirely. They gutted the game and rewrite it with the d20 engine. And as Gary had so long prophesied the spirit of the game changed, dramatically. 3.5, the final version of their first attempt, created something that while very playable and innovative in it's own right was most decidedly NOT the game we were all used to. The backlash was intense, but most of the gaming world made the shift and by 2005 D&D was largely 3.5. So much so that some gamers knew nothing else but 3.5 The d20 camp and its ideology had been fully established.
Now let's head back to the Original camp, and consider two very unique presentations of the rules. Note that the Rules Cyclopedia/Dark Dungeons and Hackmaster occupy a unique location on the spectrum of game development. The Rules Cyclopedia/Dark Dungeons really takes the Basic & Expert rules and extends and expands upon them so much that it almost equals 1e in basic technicality and not quite 2e in options.
Hackmaster on the other hand is a synthesis of 1e and 2e. While not actually Gary Gygax's missing second edition it addresses the complaints of 2e, "re-1st-e-ing"the game while preserving several popular 1e concepts/variants. Hence many call it what 3e should have been: a fix for what was broken or divergent in 2e and an advancement of the spirit of 1e. Hackmaster took the game in the direction it had been meant to go at that time.