This huge core rulebook, at over 500 pages, is so large not because it is complicated: the basic rules you will need to understand in order to play the game fill only a small portion of the book. The book is so large because it describes the setting in great detail and because it provides players with literally hundreds of options for their characters.
The Core Rules book includes 9 chapters:
History of Nuissundus (63 pages): A history of the world of Nuissundus, from the coming of the creator gods and the birth of humankind on Nuissundus, to the present day, detailing all of the major events that have shaped the world and its current nations.
Guide to Nuissundus (50 pages): Descriptions of 20 of the central nations of Nuissundus, detailing their geography and politics, and giving a brief overview of every town and city.
Character Generation (39 pages): Step by step instructions on how to generate a character for NFRP, choosing from18 races and 10 lifestyles, and a section on 'quirks' to further individualise characters.
Careers (69 pages): Full details of 140 careers for character to follow.
Game Systems (68 pages): All the rules for how to play the game, covering the game mechanic essential (like combat and travel), as well as several sections which aren't essential rules for a core book, but which provide flavour and game options (like poison, disease and traps).
Using Skills (42 pages): Descriptions of how all of the character skills function and what they allow a character to do. Skills are divided into Artisan, Knowledge, Natural, Physical, Rogue, Social and Weapon skill groups.
Religion (60 pages): The 14 major religions of the nations described in the Guide To Nuissundus chapter are featured, with details of the religion's history and origins, beliefs, rules, and clergy careers.
Magic (79 pages): All the rules for using magic in the game, and descriptions of more than 200 spells.
Money And Spending (55 pages): Prices for and descriptions of lots of services, equipment, armour and weapons.