From the opening of the PDF: This rule-set allows for introducing a few more options to your Microlite20 game, without necessarily increasing its complexity. Included are: a new skill, new races, new classes, and some other (hopefully) good stuff. It is not necessary to use Microlite20 Expert Rules in its entirety; DMs are encouraged to "cherry pick" those specific items applicable to their own campaign. Requires the use of Microlite20.