It is easy to criticize Rez from an artistic point of view; it is not as abstract as it suggests, some of the imagery is obvious and cliched, the music often dips into unremarkable trance loops, the audio to visual links are under explored.
However this is only a case for criticism because of what Rez sets itself up to be, an abstract artistic game experience in an otherwise stale commercial games industry. In this context UGA have achieved a great deal. Rez is more aggressively designed than 90% of commercial games and displays a vision that while influenced by 'cyber' classics (Tron,Tempest,Space Harrier) is unique amongst its peers.
Famously described as 'panzer dragoon with trance trousers on' by Jeff Minter (of canned Unity fame) Rez can play like a complex winamp visualizer rather than the direct synathestic interface of games like frequency. But this seems intentional as Rez takes aspects of club culture and VJing imagery to create an experience that is more dreamlike; inviting players to side-step mainstream gameplay and stereotypical formats, and to be involved in a more filmic and painterly environment.

The narrative is spare and predictable; A computer that controls the running of human civilisation has become self aware when corrupted by viri. The player takes on the role of a hacker, dispatched to penetrate the CPU defences and rectify the system. Although reminiscent of several sci-fi classics, this backdrop is explored in a thoughtful and surprisingly diverse manner. Although packed with vector graphic nostalgia throughout, the final stages of the game feature some of its best artwork, more illustrative than techno and delicately figurative.
One of the main sources of Rez's aesthetic is the work of russian painter Kandinsky. In Kandinsky's art colourful shapes and complex geometric forms represent synathestic interactions of sound and image. UGA have taken this idea and applied it to Rez but with a more iconic narrative twist. Each level of the game represents a journey through a sector of computer memory. But rather than a collection of totally abstract forms, the levels reference imagery from the memory of civilisation itself. Egyptian hieroglyphs and architecture share the gamespace with vector drawn corridors and planes. Mayan and Greek mythology also feature in the level design merged with Tron-like adversaries built from shining primitives as low-poly sea creatures swim in and out of the frame. The final area represents the stages of evolution, moving through sea bed environments to tree top vistas and finally drifting into the sky and beyond.

Although these areas are intricately designed and utilise a range of distinct colour palettes they still adhere to the some tradition (often reminding older players of the star wars trench attack) with recognisable imagery and architecture.
Only in the unlockable Oval accompanied area does the game reach towards a really abstract state. In this mode there is no score, no end and no development, simply and endless stream of alien cubes that trigger alien sound samples to play across the already dislocated ambience.
As for the other musical elements of the game; the tracks for each level are competently pre-composed and build with interesting layers and on first listen seem experimental when compared to the soundtracks of most commercial games. However they are limited due to the club based nature of the music and the simple interaction between player and the developing soundtrack. When the user detonates a chain of enemies a series of sound bursts accompany the explosions, quantized to the current beat. The sound design of these elements is superb and is the main factor in convincing the player of their interaction with the audio of the game.
Every so often the player can 'capture' a 'gateway cube' that increases both the complexity of the soundtrack and the visual environment, building to a multi layered dense audiovisual environment. The effect of this interaction is intoxicating, but the actual musical development of the current level is only marginally effected by the players actions, they cannot alter notes or rhythms, or remove elements from the track. Admittedly this helps to keep the sound artists original atmosphere, but denies the potential for a more complex and customisable gameplay experience.

Rez also boasted the use of a 'trance vibrator', an external device like a sub bass unit. This item was intended to extend the immersion and synathesia further from the screen and into the players space. Although obviously a gimmick, it was interesting to see developers experimenting with more unusual peripherals, especially in this case with a device that was an output channel rather than an alternative control mechanism.
It is commonly assumed that for Sony and Sega Rez was a 'loss leader' intended to boost the artistic credibility of the companies. Perhaps as a result of this stance it was badly promoted outside of specialist events and sold poorly, despite critical acclaim. In conclusion Rez more than fulfilled its own brief to create something audio visually unique. It may not represent the best 'game' that it could be or offer the deep level of interaction that it suggests but it still stands head and shoulders above the mainstream concepts of an artistic game experience.
www.sonicteam.com/rez/