Great job! The motion feels really good. The difficulty is about right too.
One suggestion: right now when you die, it just drops to the Mini Micro prompt, and the user has to know to enter `reboot` (or refresh the page) to try again. It'd be nice if you handled that for us — even something simple like `wait 3; reboot` might do.
Overall though this is a really nice game. I can't believe it's your first Mini Micro project!