D&D - Rules Cyclopedia -1991

The Rules Cyclopedia contained all the major rules, compiled and revised from the Dungeons & Dragons Basic Rules, as well as the Expert Rules, Companion Rules, and Master Rules boxed sets.

This was the second revision to the D&D rules. These guidelines allow a player to develop and play characters from levels 1 through 36, and includes a special section on skills. The book also contained an overview of the Known World (Mystara) and Hollow World campaign settings. It also has rules on how to convert characters between the Dungeons & Dragons game and the Advanced Dungeons & Dragons 2nd Edition (AD&D) game.
The Rules Cyclopedia includes two optional player-character classes not found in the Basic Set: the druid (introduced in the Companion ruleset and also present in AD&D from its first edition), and the mystic (introduced in the Master ruleset and similar to the monk class found in AD&D).

Rick Swan reviewed the D&D Rules Cyclopedia for Dragon magazine #184 (August 1992). He calls the book a "stunningly comprehensive volume", explaining that it "includes more detail than most GMs will ever use [...] but if you want it, you can probably find it here". According to Swan, "Best of all, the material is a joy to read, thanks to the breezy style of Aaron Allston, who must've been genetically engineered to write RPG rules. This is a must for serious fans."