This blog has an element of nostalgia to it. My first D&D rules were the D&D Basic rules edited by Tom Moldvay and with the Erol Otus cover.
The next was the D&D Expert rules edited by Frank Mentzer and with the Larry Elmore cover.
Unlike some folk, I consider the Moldvay and Mentzer printings to be the same edition with very little changes in the rules (though presentation changed greatly, obviously) and when I talk about Classic D&D I use the term for both the Moldvay and Mentzer sets - I don't think anyone with either set will have problems incorporating the new options from this blog (though whether they want to is another question).
I have dabbled in 1E AD&D, 2E AD&D and 3E D&D. Although I am not writing this blog with any of those rules sets in mind, I am quite happy for other folks to adapt and borrow as they see fit - either adapting ideas from AD&D to the Basic D&D rules or converting ideas on this blog to their prefered D&D edition. However, I will assume that folks reading and borrowing from this blog don't have AD&D or 3E, so I'll try not to include stuff that depends on having those books.
I have also got the D&D Companion Rules, the natural extension of the Mentzer Basic & Expert sets. I will be honest - I haven't really used the Companion rules in play as my Classic D&D campaigns didn't last that long. Nonetheless, I still treat most of the Companion set as part of the rules I am using. Some folks feel that B/X D&D should mean just the Moldvay Basic & Expert rules - I am not so strict. Certainly the monster, new spells and continued advancement of existing classes is welcome. However, I don't use druids - not in the same way as the Companion rules uses them - I don't take too seriously the options for companion level characters .
I've also got the Rules Cyclopedia, which gathered together all the Mentzer rulebooks into one hardback volume. It is probably the best single RPG book I have, and if I go on holiday, it is the go-to D&D book I will take. It is more compact than a DMG, PHB and MM (whichever edition) and the rules are simpler.
I will admit I was paying little attention to Classic D&D until the Old School Rennaisance - the OSR. The two most important sets of rules from my point of view, and the two that grabbed my attention in the early days, were OSRIC and Labyrinth Lord. In their early days both were free to download. This greatly improved their uptake, and I don't know if I would have looked at either of them had I been asked to pay for them.
I ended up with Labyrinth Lord, as the rules are generally simpler, and have fewer quirks and oddities carried over from the rules which they clone. These got me back thinking about the glory days of Basic D&D, the B & X series of modules, and the simplicity was a refreshing change from the splat-heavy 3E/3.5E I was getting tired of. I hope that whatever I write in this blog is as compatible with Labyrinth Lord as it is with classic D&D. I have not tried to incorporate anything from Advanced Edition Companion into this blog as I consider this blog to be primarily for B/X D&D rather than Labyrinth Lord.
OD&D is something from before my time. I have never actually picked up any of the little brown books or white box, and as such I don't feel the need to cater to that particular niche. Of course, I hope that those who do play OD&D or its retroclones will find something of use on this blog.
Although in personal campaigns and writings I have merrily converted dozens of monsters and NPCs from other games to D&D/LL, I have decided not to mess around with things that could be considered breaches of copyright on this blog. Thus I will leave alone my conversion of the monsters from the DOOM computer game, monsters and NPCs from the Fighting Fantasy gamebooks and classes and creatures from Warhammer Fantasy Battle such as skaven and chaos warriors. Besides, I'm sure that lots of other folks out there have done the same, and you can find them somewhere on the Internet.