“Butterfly sudoku” is an accessible version of the popular sudoku game, in which the user has to complete the board with appropriate butterflies in such a way that each type of butterfly appears only once in the horizontal and vertical lines. On the right side of the screen, available butterflies are displayed, which can be selected by double-pressing with the foot or hand. To place a butterfly on the board, you also need to double-click an empty field. By pressing the magnifying glass, we can check if we have successfully completed the task. There are 3 difficulty levels, each with a different number of empty fields – we recommend that new sudoku enthusiasts start with the lowest one.