Countless intangible veils separate all universes from each other - and from ours. The fabric of space and time is at its faintest, like gossamer, at these proximate points we share with all other realities. Interdimensional castaways are drawn to safety and arrive on a train in our core world, Hialao. The train system also serves as our lifeblood by connecting five other worlds to Hialao.
With the dimensional displacements not yet showing signs of slowing, and research forever futile on how to leave (besides those who simply vanish, falling back through the invisible curtain), it's impossible to say who might arrive and how they might shape this fragile series of lands, eras and cultures. Good luck out there.