This doesn't mean people aren't free to still sign up. Just kicking things off.
It was an average day in New York when the sphere was formed. A translucent purple energy formed the dome over the city.. and deep beneath the earth. While it was soon found that it allowed easy entrance exiting seemed quite impossible. Then as suddenly as the sphere formed a broadcast began on every cellphone, every tv, every computer really any device that could transmit sound or picture.
The Broadcast was of a woman, for those who could see she has dark blue hair, an artifical white skin dressed a tight black suit with thigh high boots and complicated mechanical wings on her back, she smiles, "Hi you lucky people!. I am the Dollmaker.. you might have heard of me. I keep trying to make this world a better place but time and time again those who wish you to suffer have thwarted me.
she turn and points to the screen in a fairly haruhiesque fashion, "But no more! Thanks to me and my friends you will all be lucky enough to shed the pain of age, illness and ugly forms... a beautiful immortality for all. Of course I know some will be afraid you have so many things ingrained into your meat brains to slow down rational thoughts so we aren't letting you leave.. but rest assured this will only be a temporary point in your lives... why after we finish here we will be ready to spread our joy to the rest of this world and you will be able to see your loved ones outside once we finish.."
And that's where we begin where each person has readily had access to the broadcast and knowledge of the event.