Arbiter of Wyrms said:
I did't realize that. When I started playing (c.'97), there was only AD&D 2nd ed.
When AD&D came out, TSR still supported "Basic D&D" maintaining that Advanced Dungeons and Dragons was a distinctly different game than Dungeons and Dragons, and while they had a lot of similar rules, they were marketed concurrently and were not entirely compatible. The marketing idea was that "D&D" was for kids just getting into the game and casual fans who might play on rare occasion, while "AD&D" was for older players who were much more serious and dedicated, in practice this eventually grew to be that AD&D was the version most people played (since most gamers didn't want to think of themselves as playing the simplified version) and D&D was mostly a (slightly misleading) introductory route into AD&D (playing in my first AD&D 2e game after only reading the D&D rules, since I told the DM I knew how to play "D&D" when he asked me if I wanted to join, so I had a lot of mistakes and catch-up learning to do at my first session).
The AD&D lineage is very well documented, since the current 3.5 descends from it, and it was the most popular and widely known version, but the "Basic D&D" which evolved separatlely from the Original D&D into the boxed sets and later into the Rules Cyclopedia was sold at the same time at least into the early 90's.
As some limited examples of how different "Basic D&D" was from AD&D: In Basic D&D Clerics didn't even get spellcasting until 2nd level! All the "demihuman" races were a class to themselves, if you were an Elf or a Dwarf, that was your character class (all Dwarves were fighters, all Elves were Fighter/Mages). Alignment only had Law and Chaos (although Lawfulness was presumed to be good, and Chaos was presumed to be Evil). Instead of normal progression ending at 20th level, Basic D&D went to 36th (where your character could become an Immortal and start getting levels as a godling). Instead of "Gods" you had "Immortals" which were plentiful and were even meant to be playable as PC's, and a clear way to "win" (Become a 36th level PC, become an Immortal, level up to the highest possible level of Immortal, surrender your immortality to become a 1st level mortal again, and then go all the way back up to re-earn your highest level of immortality, then you "win" as your character is consumed by a sentient, indestructable sphere of annihilation (remember the "Umbral Blot, a.k.a. Blackball" from the Epic Level Handbook? It's the source of that creature) and ascends to a new incomprehensible level of power & awareness).
Back in the late '90's when it was current, our group even then called Skills & Powers "2.5" because it seemed like such a big jump ahead in design it didn't seem like the same old edition (and in hindsight it did show design fingerprints towards 3.0).
