Microlite75 is a version of Microlite74 (Version 2.0) based on the 1974 0e edition 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. The Options & Monsters book contains a large number of optional rules a GM might elect to include in a campaign as well as monster lists and other GM-oriented information.
Note: Microlite75 was renamed Microlite74 Extended when Microlite74 Version 3.0 came out. In spite of the name, this is really a version of Microlite74. The name Microlite75 was reused for a somewhat different game with Microlite75 2.0.