Before there was Rez, there was K-Project. That was the early code name for Tetsuya Mizuguchi and United Game Artists' musical shooter, a project that evolved over time to be very different from its original concept. While the early versions of the game may only exist on someone's hard drive, a pre-release version, then known also as Project Eden and Vibes, has been released by an anonymous source as a bootable Dreamcast disc image.
The Dreamcast version of K-Project features a different soundtrack and a slew of other differences from the retail version. Collectors and Rez enthusiasts should put the Dreamcast back on the shelf and take a look.