All humans around the world lose consciousness at the same moment. When they woke up, everyone was trapped on a mysterious train - the train was speeding on endless tracks, and outside the window was the fog of chaos and nothingness.
No one knew where the train came from or where it was going. But everyone soon discovered that the train would stop at different "stations". Each site is an independent and complete world of the heavens - from ancient battlefields and steampunk wastelands to cyber cities and weird fairyland.
