The objective is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 sub-grids that compose the grid contains all of the digits from 1 to 9.
FEATURES: - four different difficulties - hundreds of puzzles for each difficulty - auto-save your progress for each puzzle - unlimited undo/redo - auto-fill drafts - clean interface and smooth controls - phones and tablets support