Pre-Revelation
The world before Revelation was much the same as our own world of the 20th century: cars, electronics, democracy, civilization. The key difference was that monsters existed in the world but were unknown to the general population at large, and you have but to look at any of a thousand modern fictions based on that premise for an explanation of that world.
The Revelation event
A terrorist movement staged an event which revealed monsters to everyone, simultaneously, all over the globe. They demonstrated a simple method for revealing monsters hidden among mortals: Mirror, Metal, Salt - A mirror to reveal vampires, a metal bar to reveal werewolves, and salt to reveal zombi. They then dramatically demonstrated this method by revealing monsters actually in the crowds at the events they had struck. With everyone in the world now possessed of the tools to detect monsters, there was no chance of a cover up. Whatever forces had existed to keep the monster world a secret were shattered all at once, and the world changed forever. This event is now referred to as Revelation.
Global Impact
When Revelation hit, chaos erupted across the civilized world. There were incidents of police being slaughtered by monsters in plain sight, and the media unfortunately gave the public the idea that monsters were sweeping the globe, destroying everything in their path. Martial law and emergency powers were quickly declared to stem the raging tide of panic. People in cities were herded into shelters under military guard to protect them from the threat of monsters, and civilization itself seemed to hover on the brink of extinction.
