Ready Player One (Ready Player One, #1)

by Ernest Cline

The Firefly universe was anchored in a sector adjacent to the Star Wars galaxy, with a detailed re-creation of the Star Trek universe in the sector adjacent to that. Users could now teleport back and forth between their favorite fictional worlds. Middle Earth. Vulcan. Pern. Arrakis. Magrathea. Discworld, Mid-World, Riverworld, Ringworld. Worlds upon worlds.

Worlds without end