Castles & Crusades
Castles & Crusades is a role-playing game published by Troll Lord Games in 2004. It was conceived as a reimagining of classic Dungeons & Dragons using streamlined mechanics from third edition Dungeons & Dragons. The game uses many of the d20 System mechanics, but eliminates skills and feats and expands the number of character classes to 13. Another feature is the reversion of some rules to the original versions seen in original Dungeons & Dragons (often referred to as "OD&D") or first edition Advanced Dungeons & Dragons (AD&D).
The system that Castles & Crusades uses is called the SIEGE Engine. A significant new mechanic is the notion of "Primes," often referred to by gamers as the 12/18 system. Through selection of character class and race, players designate some of their character's attributes as "Prime." These Prime attributes use a challenge base of 12, while non-Prime attributes use a challenge base of 18. Tasks based on the Prime attribute are therefore much easier to accomplish than those based on non-Primes. Primes allow a wider variety of characters to be created because characters of same class may excel at different types of tasks. Some players prefer to replace the different challenge bases with a +6 modifier for the Prime attributes.
The first three products produced for Castles & Crusades were an introductory boxed set, the Players Handbook, and Monsters & Treasure, a list of creatures and magic items for the game. A collection of alternate rules and guidelines for modifying the system, the Castle Keepers Guide, came out in 2008. The books have been reprinted multiple times, with more recent printings being in full color (as well as having fixed fuckups). Troll Lord games has published more than a dozen adventures for the system, and small-press publisher Goodman Games has produced three adventures for Castles & Crusades under license.
The shared lineage and resulting similarity in rules between Dungeons & Dragons, Advanced Dungeons & Dragons, Hackmaster, and Castles & Crusades simplifies conversion of rules and statistics between the games.