The developer says "Attr-X is a pointless game," and, well, he has a point; indeed, under most definitions of 'game' it does not qualify as one, since there are no objectives, either inherent or self-imposed. Think of it as a software toy, therefore.
You move about a rather large virtual world (arrow keys to move and strafe, RMB to change direction and mouselook). It is an eerie and nicely conceived virtual world; nothing like photorealistic, but also not the Tron-like setting we've become used to in many indie 3D titles. It has an abstraction, but beauty, to it, a sort of surrealist virtual world. And the world is surprisingly large, for one created by a lone-wolf developer; indeed, there are subway stations at certain locations so you can move easily from one area to another. There's also a day/night cycle, so lighting changes dramatically over time.
Equally eerie is the soundscape; sanden is a musician by training, and his primary objective was to create a soundscape you can interact with. Many objects in the world emit sounds, in a minimalist electronic music way; some, which appear to be fuzzy balls, you can pick up and move to alter the character of the sound you produce. Using a menu, you can also introduce your own, new sounds to the world.
If you don't mind pointlessness, and instead view this as an interesting world to explore, I think you'll enjoy it as an interesting aesthetic experience. I won't change your life, and I doubt you'll come back to it often, but it's both pretty and eerie enough to hold your interest for a little time at least.
Tech Note: If you're running Windows 7, I suggest installing to your documents folder, not Program Files. On start-up, the application creates a save file in the same folder as the program, which Win7 won't allow without admin permissions, and the application isn't smart enough to call the OS to ask for permission -- it simply ends with an error message. Installing in your documents folder is a simple work around, since admin privileges aren't required to write there.