I absolutely love this game, it's a great brain teaser type game. I'm really impressed that there seems to either be a massive collection of puzzles or a random generation of puzzles, I know making a valid sudoku board is difficult, and adding in the complexity of one tile being wrong is very impressive that you were able to get it working. I think the main suggestion I'd give would to make it so that the space key can switch between pen/note modes, so that players can exclusively use the keyboard for the whole game and not have to swap between the two settings with the mouse since you then have to click back into the board to continue.
Viewing post in Su-NO-ku jam comments
Thanks! I'll admit I was using a package to generate the sudoku and only then added the incorrect clue
As far as the keys, I a) forgot to put in the description that you can use P to switch to pen and N to switch to notes! and b) tried, but wasn't able to get the selected box to refocus after clicking one of the inputs below. B is something I intend to work on after the jam, and I can probably edit the description right now so thanks for letting me know!