Loved it. Being upside down was a bit confusing but could have been made into some interesting puzzles in the future. In terms of UI I didn't appreciate the selected task appearing anywhere randomly on the bottom of the screen, my eyes/attention are on the right hand side of the screen when I'm selecting so it's a long way to travel (both with my eyes and mouse) when the selected box appears all the way over on the far bottom left of the screen. I would suggest having the loop further to the left (if you don't want to keep it dead centre) and all your selections appear to the right hand side of it.
Otherwise, nice concept. Level 5 took me a while and was therefore satisfying when I finally achieved it. Could you maintain a list of previously tried sequences that failed? I had a hard time remembering which combinations I'd already tried.