Rez is a musical rail shooter developed by United Game Artists and published by Sega for the Dreamcast and PlayStation 2. It was released in Japan on November 2001, followed by releases to the United States and Europe in January 2002. The game has since seen two remasters: Rez HD, released to the Xbox Live Arcade in 2008, and Rez Infinite, developed for PlayStation VR and released to the PlayStation Network in October 2016 and Microsoft Windows in August 2017. Inspired by the work of Russian painter, Wassily Kandinsky, the game was developed under the working title K-Project, and was conceptualized and produced by Tetsuya Mizuguchi. Rez is notable for replacing the typical sound effects found in most rail shooters with electronic music. The player creates sounds and melodies as they target and destroy foes in the game, leading to a form of synesthesia.

The game’s development team contained several former members of the disbanded Team Andromeda, the Sega development team behind the Panzer Dragoon series. Rez Infinite, the latest version of the game created for virtual reality, was released to widespread acclaim, and is widely considered to be one of the best VR games to date.

In 2007, a beta-build version of Rez was released for the Sega Dreamcast exclusively in Japan, titled Vibes as a promotional item for the then-upcoming Rez HD for the Xbox 360.