What you did perfectly is hit the appeal factor in people. This game is relaxing with a touch of simplicity with the music fitting very well by setting the ambiance. It's more of a reflex challenge that gets harder as you go, which is good, but at times I find sharp movements to be unresponsive which kills the game slightly. But, this game is very very basic with no change beyond difficulty. No background really, the overall game just has nothing when the controls are shoddy (occasionally, but mostly on the sharp turns which are most important.) This is where the appeal comes in, with the music being simple and having a gentle centered character, people will call this "beautiful" (I'm not reading beyond my own review) which in combination of relaxation and contrast of a lot of violent games that people like to... not demonize, but view under a veil of negativity. It is nice to play, I will give it that.
TL;DR
Ok, not much to it, improve controls, and music is good. Appeal is huge considering the general audience and mixed views on simple and or non-violent games. Not playing again probably due to lack of changes in levels beyond difficulty.