Simulacron 3 by Daniel F. Galouye
This science fiction novel explores the concept of virtual reality and the nature of reality itself, set in a world where a computer simulation, designed to predict consumer trends, evolves into a fully immersive virtual city. The protagonist, a programmer involved with the project, discovers unsettling evidence that his own reality might also be a simulation, leading him on a quest to uncover the truth. As he delves deeper, he faces existential questions and the challenge of distinguishing between the simulated and the real, pushing the boundaries of human perception and technology. The narrative delves into themes of consciousness, identity, and the ethical implications of creating simulated realities.