Very good! Beaten all of the levels here. The Reindeer was harder than the last one though.
It was the most engaging game I've played until now from the jam, it's quite solid.
I'd only put the time score after you complete a level on top of a gray/black rectangle so it would be more noticeable, since I only saw my time score on the last level.
Also I didn't pay much attention to this detail, but I do believe the music stopped looping at some point, I'm not 100% sure though.
I'd recommend adding a "X" input to the right mouse button so we mark where there shouldn't be squares. It would help a lot.
Overall awesome game! Picross is always nice to have.