>>43272108LotFP is an OSR game, basically James Raggi's houseruled Basic D&D, named after the heavy metal fanzine he used to run. It's garnered a lot of attention and a number of awards, especially for its modules, which are really good.
The core rules are tight, well-designed, and simple. It has four basic classes, Fighter, Cleric, Magic User, and Specialist, with strong role protection between them. The Specialist is Raggi's own version of the Thief, reworked into a dungeon crawling expert, and is one of the best versions of the Thief I've seen.
LotFP's stock setting focuses on a 17th century mileu, with excellent rules for firearms -- unusual for a D&D based game.
Little of the setting is found in the core books, however. It's mostly in the modules, which are fantastic, if rather edgy in the way a metal album cover is.
Have the free version of the basic rules.
You can find more about it in the OSR generals, where it's discussed quite a bit.
