Chivalry and Sorcery has been around a long time, being initially published in 1977 by Fantasy Games Unlimited. It's an appealing game that may be played at many levels and in many ways, from high fantasy right through to grimly-realistic mediaeval life.
The character generation system can be daunting, but if viewed as an adventure in itself results in characters that are as rounded and well-developed as their players! Even once you have your character ready to go, it pays for both players and GM to have a good grasp of how the system works (especially if you have magic in the game) or you will spend a lot of time browsing your books... but if this sounds negative, if you are prepared to make a modicum of effort it is an excellent game that feels as if it is really happening.
One of the things I particularly like is the modular nature of the game. As you plan your campaign, you can decide whether or not magic works, will priests be able to heal by 'supernatural' powers bestowed by their deities, do elves or dwarves exist and so on... but whatever you put in or leave out, the game remains balanced! If you don't want a 'real world' setting, there's a world called Arden to explore.
A Second Edition was brought out in 1983, again by FGU. It is an updated and more organised version of the original rules, with few substantive changes. Three time periods - Early, High, and Late Feudal - were provided, each with their own level of technological advancement. The Third Edition was far more fantasy-oriented, released in 1996 by Highlander Designs, a company founded by one of the game's creators. Magic was simplified dramatically and historical realism was largely abandoned. A cut-down taster version called Chivalry and Sorcery Light was produced in 1999, but a lack of support and other reasons led to the eventual demise of Highlander Designs.
The torch was passed to UK company Brittania Game Designs, who brought out a Fourth Edition, also called Rebirth, in 2000. The core rules talk about both historical mediaeval and high fantasy settings, while sourcebooks and adventures support a detailed fantasy world called Marakush (also home to the 'Heroes of Marakush' CSC). The books about elves and dwarves leave their homelands open, Marakush or any other fantasy world of your choice.