Speed Sudoku Four

How to play

1. Fill the grid so every row, every column and every 2 by 2 box contains the numbers 1 to 4 exactly once.
2. Tap a cell, then tap a number or press 1 to 4 on your keyboard. Backspace or the clear button empties a cell.
3. The clock starts on your first move. Check marks mistakes and Hint fills in one correct cell, and both are counted on your result.
4. Every grid has a single solution, so you never need to guess. Pure logic always finishes it.

Tips and strategy

• Start with the row, column or box that already has the most numbers, because it has the fewest options left.
• If a number can only go in one cell of a row, column or box, it has to go there.
• Work through each number in turn. Placing every 1, then every 2, often unlocks the rest.
• Use arrow keys to move between cells without lifting your hands from the number keys.