Re: OOC Thread for General Use (2)
It's an expansion of the early, three-level boxed starter set put out by TSR in the late 70s, under the name "Dungeons & Dragons," and the original rulebook had blue-and-white covers, although the same image appeared on the cover of the box in full color. The original set came with sufficient rules to play from first through third level of experience with a limited set of character options (fighter, cleric, thief, and magic-user were all human, and demi-humans were as much a race as a class with elves (fighter/wizards), halflings (short fighters), and dwarves (grumpy, short fighters with some stone-related abilities)), some chits for randomization, and an introductory adventure ("B1: Into the Unknown", if I recall correctly).
The set was expanded into Basic (red box, character levels 1-3) and Expert (blue box, character levels 4-14) sets by Tom Moldvay in the early 1980s, due to demand from consumers, and several modules were published to go with them, including the seminal "X1: The Isle of Dread" and "B2: The Keep on the Borderlands".
Just a year or two later the series was revamped under Frank Mentzer, and included Companion-level rules (levels 15-25), Master-level rules (levels 26-36), and Immortal-level rules (actually immortal characters, with a tiered system of advancement that was wholly different from the prior leveling setup). Even more modules were produced, although, as is normal, the highest level modules were rarely played, since most characters were never played for long enough to go through them.
Numerous retroclones exist, although PDF copies of the originals are available for relatively little money on DriveThruRPG. It wasn't AD&D, but held some similarities, and was a generally simpler game.