Nice idea, hard levels
First of all i must say that musics are really good, it makes one keep playing until he really gets annoyed with the difficulty:D but there seems to be a problem with the push and pull forces (or it is really like this in atomic sense:D), yet makes no difference since this is a game and is meant to have fun where a difficulty ladder should be present through levels.
And a suggestion for improvement:
When trace is on, make it last until the next "go". I mean, I'd like to insert new charges according to the trace and when i "stop" trace wears off and I can adjust my charges by what i remember of the trace line. In short, if you make the trace line last until next run (not when "stop" is clicked), it'd help much more.