Wow, there's some hard puzzle here! A 'Continue' options would be great.
Nice evolution of a classic concept. I like it!
Thank you! I did think about a "continue" option -- the main reason I don't have it is that I couldn't see anywhere obvious to put it in the UI, but what someone else suggested is a whole new screen for "level select", which is a good idea and is probably the way I should solve this in future versions!