This was nice (and a little addictive)! I only have 2 suggestions:
1) maybe give the player a number of tries before the level resets on its own
AND/OR
2) when the player doesn't succeed, add an overlay that says "failed" or "restart". This is because when I was on Level 1, I thought that I could keep trying without restarting the level. So, I was a little confused at first.
Other than those two things, I liked this!