From publisher blurb:
This new Advanced Knights of the All Mind Players Book combines various home brew rules adopted from a variety of influences with the Open Gaming License System Reference Documents. Primarily this work is based on v.5.1, but there are also small amounts of discrete rules from v.3.5.
The tome presents a unified rulebook for players with added new rules directly descended from old-style gaming such as critical hits tables, fumbles tables, divine interventions, technological weapons, insect, amphibian, and reptilian races, and new character classes. However, it is much less a "hack" per se than subtle departures from what a player would obtain from purchasing the mainstream version of rules that would include v.5.1 or downloading the free version of v.5.1 rules. Ha, of course one would miss the art.
Also included is a very simple, 70's-style character sheet for players.