In Ernest Cline’s Ready Player One, the virtual world is called the OASIS.
Published in 2011, the novel is set in a dystopian future where many people spend much of their time inside the OASIS, a vast networked virtual reality. Users can attend school, work, socialize, explore fictional environments, and play games there.
The story begins after OASIS creator James Halliday dies and leaves behind a contest. He hides an Easter egg within the virtual world, and the first person to find it will inherit his fortune and control of the OASIS. Wade Watts, using the avatar name Parzival, becomes one of the contestants pursuing the clues.
The OASIS is not the same as the Matrix from William Gibson’s or later film-related cyberpunk traditions. “Metaverse” is a broader term for persistent virtual worlds, while New Genesis is a fictional planet in DC Comics. Ready Player One is often shelved with science fiction, but its quest structure and immersive invented world make it a common fantasy-adjacent trivia subject.