Thanks a lot for your feedback. I‘ve implemented most of your suggestions in the latest build. 
The winning animation will have to wait a bit longer as I haven‘t had the right idea for it yet.
Out of curiosity, do you use
playdate.stop()?
I‘ll try playdate.stop() at some point but first I‘ll have to figure out how to not break my animations which are currently tied to playdate.update.
What is your plan for sharing puzzle between users?
I don‘t think I‘d ever run a server for sharing but if Playdates could exchange puzzle directly via wifi or bluethooth that would be amazing.