The advanced rules supplement for the Shadowrun game as a whole, most of this book expands existing rules, adds optional new ones, and clarifies others. It is in no way required to play the game, but it's quite a good add-on to increase the scope of the game itself as well as of the game world. Among the topics covered are a whole new character generation system (points-based, rather than a priority system), edges and flaws to make a character more unique, new metahuman races, a new skill web, rules for learning and improving skills (making this more involved than just spending Good Karma), and more.