Won a game! Ok, now it’s by far more user-friendly and doesn’t take too much effort and distraction :) I guess the difficulty level is a bit inconsistent - Middle starts way too easy, but the previous attempt was above my Sudoku skills to finish (the dependencies got too convoluted to solve without “trying one direction” but as ctrl+z here goes back only one step, returning to the original position would be problematic). Next puzzle was almost trivial, however, I’m not sure if I did some mistake or is there no win notification for finishing the puzzle?