NEOCLASSICAL GEEK REVIVAL, 5th Edition
Default Genre: Fantasy
Minimum number of books needed to play: 1
Dice used: d20, d12, d10, d8, d6 and d4.
Learning Curve*: Medium
Available as: PDF, Print of Demand Paperback, and Leatherbound Hardback
Supplements/Modules/Adventures available: Several
*Learning Curve is my estimate of how hard it might be to learn the system, assuming you started with D&D, Pathfinder, or one of its clones. Levels include Easy, Medium, Hard and Existential Insane-o.