From the Publisher's Website:
Pith is a role-playing system designed to provide a generic set of game mechanics suitable, or quickly adaptable, to any setting. It is a no-frills core system – hence the name – and it assumes the reader is familiar with role-playing games in general. It includes rules for character generation and development, dice rolls to perform feats based on Attributes and Skills, and close-up and distance combat. There are also comprehensive rules for a generic form of supernatural activity referred to as MOSLI – Magic Or Something Like It. This could relate to magic in a fantasy setting, the occult in a modern-world setting, or psionic powers in a science fiction setting. There are examples of weapons and armour to guide the Game Master (GM), a few miscellaneous rules, and a little guidance on creating your own settings.
Pith is a bare-bones system that seeks to balance a satisfactory degree of realism with ready playability. Character management, rolls, MOSLI and combat have all been designed to be interesting for the players, yet universally applicable.
What is not included is any particular setting. World details, non-human races, monsters and details of equipment and economics must be provided by the GM, if needed, though this work is creative rather than mechanical. However, the detached and universal nature of the rules gives the GM and the players the freedom to enjoy adventures in any setting, without purchasing extra materials or learning new systems. Characters could even transfer from one setting to another without adjustment.
Pith also permits the GM to choose the die used for Attribute and Skill rolls, so that the degree of chance in a particular role-playing session can be readily controlled. This unusual feature contributes to different ‘styles’ of play – from serious and realistic to lightweight and fun.
Pith itself is free and always will be.