Obviously, I'm biased. But Modos RPG is my favorite. My signature contains a URL to the under-construction document/rulebook in these forums.
It's a generic, rules-light system. That's intentional: you're supposed to add your own flavor, rules, adventures, or settings, or use someone else's.
The rules are complete, and feature:
- Roleplaying flexibility. Does your character's high Physical score mean he's quick, tough, or mighty? Up to you!
- Class flexibility. Anyone can cast a spell, swing a sword, pick locks, or wear heavy armor. It all depends on how you build your character.
- Power flexibility. Whether you wave your hands around in a robe to cast a spell, or just look at someone the wrong way and make him fall asleep while drinking a latte, is also up to you.
- GM flexibility (also rules-lightness). There's only one table for combat modifiers, situational bonuses, and (most) skill adjudication: difficulty. The difficulty table asks: how hard would a task be for the average person? Pick a modifier in the right ballpark, and roll with it.
The rulebook is NOT complete, because I (we) need to add:
- Spells (powers) beyond 3rd level.
- More monsters.
- The sample rules module.
- The rules catalog (short-hand rules, which make it really simple to add, alter, and remove rules).
- A couple other appendices.
If you don't mind an early-version (v 1.1), free RPG, take it and run!