Rez

Rez is a video game that combines mechanics from the music game genre and rail shooters like Panzer Dragoon. Players take the role of a hacker infiltrating a malfunctioning artificial intelligence and fighting off viruses and corrupted security programs. Destroying data nodes in each level raises the "layer level" to a maximum number of 10. Raising a layer level changes the background music, layout, and enemies of a level. There are five levels, dubbed Areas, although at the start only four can be accessed.

The player character can assume six forms at different power levels, with a seventh unlocked for Area 5. The player starts the game by default at Level 01. Upon being damaged, the player devolves into a previous form. The lowest possible is Level 00, and if hit again in this state the game ends.

The narrative of Rez is told without dialogue and using minimal description, relying on in-game visual storytelling. In the future, amid a rising population and an overflowing amount of information corrupting cyberspace, a new network dubbed "K Project" is created to manage the data. At the heart of K Project is an artificial intelligence called Eden. Overwhelmed by the ever-increasing flow of information, Eden begins doubting its purpose and existence, withdrawing into sleep at the heart of cyberspace when finally confronted with humanity's clashing nature and actions in the real world.

The player, a hacker, dives into cyberspace and fights off viruses and infected firewalls to find and wake Eden. When they reach the final area, the hacker is confronted with questions about the meaning of life, then after a final battle succeeds in reconstituting and waking Eden.

Rez was developed by United Game Artists, an internal studio of Sega led by Tetsuya Mizuguchi, who was then known for his work on racing games. The original concept for Rez originated between 1994 and 1995. During research work in Europe on Sega Rally Championship 2, Mizuguchi and a few friends attended the open-air music event Street Parade. Seeing people swaying en masse to the music, he decided that this was the type of game he wished to make.

At this time, the technology was inadequate for realising his vision. In 1998, Mizuguchi was approached about forming a dedicated team to work on new innovative titles for Sega's new Dreamcast console; his first project along these lines was Space Channel 5, and during its production he made plans for Rez. He built up his new team at what would become United Game Artists. As with Space Channel 5, Mizuguchi wanted to draw in casual gamers from across demographics, along with people who would normally not play games.

Sega originally shipped Rez in fairly small quantities. In Japan, the PS2 version sold just under 37,600 units. By 2003, the PlayStation 2 version had sold over 100,000 copies in North America. Although generally low, North American sales were worse than in Japan, though Mizuguchi held out hope for European sales. On the whole, Rez was classified as a commercial failure worldwide, blamed alternately on poor marketing support from Sega, and its non-standard gameplay and art style.

Japanese gaming magazine Famitsu reviewed both versions of the game in the same issue. In their PS2 version review, Famitsu praised its combination of rail shooter and music genre mechanics while also praising the visual design. The Dreamcast version was given one point less than the PS2 version, with a reviewer citing the added gameplay immersion from the Trance Vibrator as the reason for the PS2 version's higher score.

Despite low sales, a sequel to Rez was being planned at Sega prior to its internal restructuring. Mizuguchi has continued to expand upon his game designs, aiming to bring in casual players and have them experience synesthesia as he wanted to do with Rez. The Ubisoft-published Child of Eden is a spiritual successor to Rez, designed around the same gameplay and sensory principles. Mizuguchi envisioned Rez as being the first in a trilogy of similar titles. According to a 2017 interview, Area X was seen by him partly as a prototype for the conceptual third title.