The ADOM Guidebook is intended to be a definitive reference for ADOM and as such contains spoilers throughout. There is no provision made to protect newer players from spoilers, so if you want to figure out the game for yourself, this guide is not appropriate.
The Guidebook started as simply ASCII, but has been expanded to take advantage of the more advanced features that HTML offers. HTML and ASCII compilations are available for download and offline reference. The ASCII compilation is circa 2005 and therefore contains errors and omissions. A newer version may someday be generated but is a low priority.
There are archives of the 1.0.0 and gamma 16 prerelease 2 versions available in Appendix N.
The historical work on the Guidebook was done by the Usenet newsgroup rec.games.roguelike.adom but today most players frequent Thomas Biskup's official ADOM site.