I love this. Managed to finish it in about 5 minutes. Level 11 is much harder than some of the levels that follow it. But I had great fun. The right balance of frustration and satisfaction of finally pulling off a hard level.
Also: Your design, presentation, and use of the mouse limitation is perfect. And you just jump straight into it: No nonsense, pure gameplay.
Even the frantic music. It's perfect. Keeps you going.
What a submission.