Sudoku Difficult

Empty squares leave very few anchors on this 9x9 grid. Sudoku Difficult uses a single hard puzzle layout, backed by soft sound effects and a strange bird waiting beside the board. The classic number puzzle stays strict here. Missing digits are scarce, and the board gives little room for trial and error. Pencil marks are the only aid available. No hints appear, and no row, column, or 3x3 area receives extra highlighting. That setup makes this version fit players who already know Sudoku rules and want a tougher number game.

How to play?

Place digits into the empty cells until the whole grid is filled. Repeat numbers nowhere in a row, nowhere in a column, and nowhere inside any 3x3 box. Read the given numbers first, then add notes inside squares to test possible values. Wrong placement ends the attempt. The board resets, and the puzzle must be solved again from the beginning.