From the back of the book:
Following planetary geomagnetic reversal, successive waves of catastrophic events pounded the continents without reprieve over the course of nearly a year. Fire fell from the skies, crashing to the ground, exposing giant chasms that had apparently lain dormant and undiscovered for aeons. Plagues swept the lands, indiscriminately thinning the ranks of humans. Seismic eruptions toppled skyscrapers and sent towering tsunamis crashing against densely inhabited coastal cities. Around the world, loss of life was catastrophic. Making matters worse, reports began streaming in from areas surrounding the great chasms of strange humanoid, even demonic beings permeating the wilderness. At the same time, ascetics around the world began having revelations, even claiming to have unlocked the secrets to wielding godly power and conjuring miracles.
Years have passed and the world is still rebuilding from the great Tribulation of eight years prior. From the ashes of Manhattan Island, the new city of Halcyon is being constructed. In this new city of opportunity, beneath the towering skyscrapers and the gleaming arcology, wars have begun over who will claim the spoils and rise to power in what is to become the keystone city of the Federation. The Federation and its military, foreign governments, megacorporations, organized crime syndicates, arms dealers, drug runners, fanatics, anarchists, and countless other factions all enter the fray to control the rise (or demise) of Halcyon and place their claim on the future of civilization. All eyes are upon this highly-coveted and contested city-state. And for good reason.
As Halcyon goes, so does the world.
The Players Codex is a complete rulebook for GMs and players. This book contains core concepts, character races, character creation rules, skills, game mechanics, magic rules, spell and summoning lists, historical narrative, designer notes, GM guide, campaign design guide, creatures & NPCs, and advanced rules along with a load of equipment and vehicle listings.