Sudoku4k is an addictive Sudoku puzzle game. You get 1000+ challenging Sudoku number puzzles to train your brain Classic Sudoku the puzzle games for your brain, memory and logical thinking. How To Play 1. To start a free game, please select the difficulty required. 2. You will see a 9x9 grid, which contains 9 3x3 boxes. Some squares already contain numbers. 3. To complete the puzzle, you must fill each block on the grid with 1-9 numbers. 4. The numbers 1-9 should appear exactly once in each row, column, and box 3 x 3. Key Features 1. Sudoku puzzles come in 4 difficulty levels - easy, medium, hard and expert! Perfect for Sudoku beginners and advanced players! 2. Intelligent Hints - Get hints when you are stuck 3. Note tracker to track your notes 4. Erase notes. 5. Highlight Duplicates to avoid repeating numbers in a row, column and block. 6. Undo your moves to revert back to the previous states. 7. Keep record of your best time and average time in every difficulty levels. 8. Relaxing and calming background music. 9. No Wifi games, play offline and without internet.