I tried out a free one-hour demo of Chromadrome 2 in order to write a review for another site, and I liked the game so much that I bought the full version!
The concept is very simple. In the game, you are a gold ball (with big eyes) that travels down a track. The object of the game is to stay on the track and not fall off. The more tracks you complete, the more challenges appear -- jumps, loop-the-loops, obstacles, etc. There is also an "Academy" where you can practice your moves.
What makes the game so much fun, and so addicting, are the mesmerizing abstract visualizations that move in time to the music (you can use the music that comes with the game, or you can use your own), and the excitement of some of the moves (going around the loop-de-loops feels like being on a roller coaster).
If this sounds interesting to you, I recommend trying out the demo. That gives you the complete game, though only for an hour.