Ouroboros Tabletop Roleplaying Engine, Third Iteration (2012)

From publisher blurb:

This is a rules engine designed for use in fantasy roleplaying. Features of the core mechanism:

• Resolution uses a small pool of d20s, attempting to score equal or under an attribute.
• It's very easy for the Guide to present interesting choices and complex situations as single rolls, by setting up the dangers and opportnities each roll provides - and for players to decide not just "IF they do well" but "HOW they do well" when stakes like that are played out.
• "Breath" is used as a means of tracking encumbrance and weariness, as stunt points, and for use in social action.

This engine doesn't include a setting, introduction to roleplaying, or precdure for building gaming situations. These are available for download, however:
1. Fundamentals of Tabletop Roleplaying, Second Iteration, a guide to the very basics of playing tabletop RPGs.

2. Tenocha: The Old Empire, Second Iteration, a fantastic setting for roleplay.

3. Situations For Tabletop Roleplaying, Second Iteration, a collection of methods for building good situations for tabletop gaming.