Geoffrey McKinney's recent post on the OD&D forum (read it here) talks about some of the strangest and most infamous of old-school games, the original Arduin trilogy. I've had the books for months and read them off and on, and I occasionally get the desire to just rip off big chunks and run with them in D&D. I still have the sort of eyes that read the reduced typeface of the original trilogy, although I may be tempted by the allure of a single hardcover volume (available here) in the future.
Arduin was marketed as its own game, to a certain extent, but fundamentally it was David Hargrave's house rules for the original D&D game. It's interesting to look through it, almost to the point where I think it should be required reading for people talking about OD&D in this day and age. Like most gamers at the time, Hargrave cheerfully embraced the OD&D supplements, hacking and modifying away at bits of them rather than taking the very modern stance of embracing "just the original 3 rulebooks." It's also rather accurate as a snapshot of the kind of thing that gamers, at least the sort who wrote in to Alarums & Excursions, were doing at the time: there are charts for character special abilities, critical hits, a mana point system, and concerns about all those areas where OD&D wasn't really clear.
But beyond that, Arduin reflects certain realities about the time that OD&D was out that weren't true about the subsequent period. Hargrave was very conscious that he wasn't writing eternal rules down to the ages. His tone is constantly that of one participant in the larger conversation about how to do things – albeit a participant who'd gotten himself a bully pulpit by publishing his rules as a supplement. And this was the reality of the gaming scene at the time: TSR was regarded as having a great product, but nobody was poring through the works of Gygax for hidden pearls of wisdom; his ideas were regarded as nothing more than one way to do things. What I think people miss is that this is the context of the publication of AD&D as we know it. Into this volatile stew of gamers taking D&D off in varied and colorful directions, in which Tunnels & Trolls was considered about as good as the "real thing", Gygax launched a set of hardbound rule books that really solidified a lot of the play culture to come afterward. But the AD&D books have every mark of being birthed in this ongoing milieu; the game was then wrenched out of it by sudden fad status, and the idea of a set in stone "D&D" replaced it.
Arduin, because it's back in print, serves as a living reminder that the game wasn't always that way. Even if you don't embrace a single thing from its rules (although how anyone can pass up air sharks is beyond me), the more important thing is to look at the original D&D game as it was seen in its early days. Sometimes I think that the best thing we can do in the old-school renaissance is to create a dozen or two Arduins, reinterpretations of D&D that expand on the wild possibilities in the game rather than constraining ourselves to trying to understand and appreciate what Gygax managed to put into the first three D&D books ever published.