Serious Sudoku

	1	2	3	4
5	6	7	8	9

How to play

Tap a cell, then tap a digit to set it. Digits that conflict with the row, column or block are greyed out. Given digits are black, digits you set are blue.

Tapping a cell that contains a digit highlights its row, column and block in light red, the same digit elsewhere in red, and the empty cells that still have this digit as a pencil mark in green.

Number pad

Clear the selected cell (digit and pencil marks).
Pencil mode: digits toggle small pencil marks instead of setting the cell. Marks that become impossible are removed automatically.
Undo the last action.

Buttons below the sudoku

Start a new sudoku and choose its level, from the easiest to the hardest.
Guess a digit, see below.
Reject the last guess, see below.
Open the tools, see below.

Tools

Fill in pencil marks: All digits that are still possible are added to every empty cell. Counts as help used.
Restart: The current sudoku is started again, all progress is lost.
Find mistakes: Digits that differ from the solution are marked in red. Counts as help used.
Solve: The solution is filled in. It is not recorded in the history.
Input own sudoku: The grid is emptied, then set the digits you want and tap the check mark below the sudoku (or choose “Finish input” in the tools). Custom sudokus are not recorded in the history.

Guessing

For difficult sudokus you sometimes get stuck and have to guess. Tap the branch button and then a digit: the digit is a guess and shown in green. All digits set so far are fixed (black) and assumed to be correct, this is a save point. If the guess leads to a contradiction, everything done since the last guess is reverted with the cross button. You can make another guess inside a guess.

Time and history

When you finish a sudoku, it is recorded in the history (menu). The current game is saved on your device, so you can close the app and continue later. The timer can be hidden in the settings (menu).

Serious Sudoku

Select level:

Restart game?

Tools

Solved!