Rez is set in the near future on a massively overpopulated Earth, its society buckling under soaring crime and teetering on the edge of meltdown. In an effort to restore order, a new global network was built — Project-K — overseen by a self-aware artificial intelligence named Eden. But the ever-swelling flow of information, and infection by a virus (the player), threw Eden into confusion, leading her to question the meaning of her own existence and the consequences of her actions. Overwhelmed by the paradoxes surrounding her and the power she wielded, she shut herself down.
The player controls a hacker virus unofficially named Swayzak, traversing the Project-K network on a mission to reawaken Eden and reveal the true being at her core — pressing ever deeper into the system while destroying the other viruses, anti-viruses, security programs, defense systems, and firewalls in the way.