Sudoku is a wonderful logic-based game that you can try anywhere to keep your brain sharp. Conceptis MultiSudoku for iPhone takes it to the next level by letting you try multi-grid Sudoku variations on-the-go. It has 2 to 5 grid puzzles with multiple difficulty levels.
This app comes with 72 puzzle samples to get you started. It lets you play and save multiple puzzles concurrently. It supports “pencil marks” for harder puzzles and unlimited undo/redos. Conceptis MultiSudoku also tracks your puzzle solving times.[where to get it]