I can't figure out a way to take notes in the puzzles - putting the possible numbers in the square before I actually get the one single correct number. Is there a way to do this I'm missing?

Please make it so that when the player selects a number or letter to highlight that it also highlights squares where it appears in notes. This would make the 16 and 25 size puzzles much less difficult.

The color scheme could use more contract, bright white and yellow are too similar. Maybe green for the numbers that are filled in. Please consider an option to have a white background with the prefilled numbers in black. Also the use of a different font for prefilled and user filled squares seems kind of buggy as it often reverts to both kinds of squares using the same font....

That would be an awesome addition.

The screenshots didn't show any.