Hey yeah it's not too bad
My suggestions would be:
1. Change the background colour based on your deviation from the line, or at least when you are getting far from the line (I felt like the game end rather abruptly)
2. Maybe have a health bar that you lose health from each time you go off the bar
3. Some kind of bonus points system, like having 2 paths fork off the trace, one of which is harder to follow and gives you more points, the other which is easier so you're less likely to die. And/or you could have bonus icons that appear on the line temporarily, that you have to move quickly to get.