From Introduction:
Steel and Stealth is an OGL rules resource that greatly expands four core classes: the fighter, monk, ranger and rogue. These are the universal versions of each class. Each universal class is a framework that lets players choose from a variety of special abilities. You can use these advancements to replicate the standard core classes (and you can, in fact, run standard characters alongside universal class characters) or you can develop your own unique combination of abilities.
Think of the rules herein as a midway point between the tightly defined niches of the standard core classes and generic “point buy” systems. Great care has been taken to leave each class with its own, unique niche. A fighter is still devoted to armed combat in all forms. Rangers are still supreme survivalists, rogues are still sneaky and monks are still masters of stylized fighting.
These four classes are classic pulp fantasy protagonists: mercenary swordsmen, sardonic thieves, tough wanderers and exotic adventurers. Steel and Stealth can be used to build a campaign that focuses on such characters, ensuring that while every PC cleaves to common thieves, no two are exactly alike.