From the Back Cover:
Microlite74 games are trimmed-down miniature versions of the Primary Fantasy SRD rules designed to be quick and easy to play, especially when compared to modern incarnations of the game. The goal of Microlite74 games is to recreate the style and feel of that very first ("0e") fantasy roleplaying game published back in 1974 without giving up all of the clearer mechanics of modern D20-based versions.
The Microlite74 rules are based on the 1974 0e edition of the world's most popular fantasy roleplaying game with its supplements and material from 0e magazine articles, some 0e third party material, some of the house rules the author used in the 1970s, and selected ideas from other roleplaying games. These rules are not intended to be a clone of the 0e rules, but rather a conversion of them to a rules-lite D20-based system that encourages old-school play without strictly old-school rules.
Microlite74 Companion 1: Optional Rules contains a large number of optional rules a GM may elect to include in a campaign. Each optional rules section is independent and can be included or excluded on its own. Most optional rules are usable with any of the three versions of Microlite74: Basic, Standard, or Extended.
This book includes optional rules for:
Stats, races, classes, class Abilities, advantages and disadvantages
Traditional saving rolls, skills and talents
Metamagic, ritual magic, counterspells, weird science, fire-and-forget magic
Combat stunts, armor for all classes, weapon damage by class, minis and battlemats,
Action points, fame, sanity, aspects,
Psionics, spirits (combat, powers, and binding),
Fixed level campaigns, science fantasy, and more.