A-tube 数独

A-tube Sudoku is a classic Sudoku game that is completely free, with no advertisements and no in-app purchases. Choose from three difficulty levels: Beginner, Advanced, and Expert. You can also switch between the Tile Board and Minimal Board styles. The game features large numbers and clear 3×3 grid boundaries, optimized for touch controls on both iPhone and iPad. The rules are straightforward: you may continue the challenge after your first three mistakes. After the fourth mistake, your score is frozen, but you can still complete the puzzle. Beginner difficulty includes an Undo feature, while Advanced and Expert offer a greater challenge. The local leaderboard records scores on the current device. The online leaderboard displays rankings with public nicknames and scores. No password is required—simply enter a nickname to start playing.