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You can select cells by pressing on them. If you hold down your mouse and drag, you can select several.

You can also press ctrl (or cmd on mac) and press on cells, which will then add them to your selection.

You can also use your mouse arrows to move around the grid.

You can use the following shortcuts:

- z for numbers
- x for cornermarks
- c for centermarks
- v for colors
- b for notes

You input a number or a value, by selecting one or more cells and pressing a number from 0-9 or by pressing the numbers on the controller on the right. Press the backspace button to remove the value

You create cornermarks by selecting a cell and pressing the numbers you want to mark. You can use both the keyboard and the controls on the right. Press the backspace button to remove the cornermarks

You create centermarks by selecting a cell and pressing the numbers you want to mark. You can use both the keyboard and the controls on the right. Press the backspace button to remove the centermarks

You add colors like you add numbers. The numbers 0-9 match the colors on the right, if you want to use your keyboard instead. Press the backspace button to remove the color

You can add notes as annotations to any cell to record information that cannot be communicated using the standard pencil mark tools. Cells with with notes will display a marker in the top right corner. Hovering over the marker will show the saved text. Press the backspace button to remove the note

The scanning tool can be used to help solve the puzzle by checking whether any cells are restricted to a single digit due to the puzzle rules, or to quickly clean up pencil marks after placing a digit. With Auto-scanning enabled, the scanner will run immediately every time a digit is entered - editing pencil marks will not trigger a scan.

Press (s) to start or stop the scanner.

Press (a) to make a single step.

Press (h) to toggle highlighting on or off.

Press (t) to toggle Tuple highlighting on or off

*Highlighting Mode**None*: No additional cells are highlighted when the selected cells in the grid are changed.

*Seen*: Highlight any cells which are seen by the currently selected cell. If multiple cells are selected, only those cells seen by every cell in the selection are highlighted.

*Tuples*: Highlight any cells which form a Tuple with the currently selected cell.*Scanning Mode**Basic*: The scanner will only use the basic rules of Sudoku when checking available digits.

*Advanced*: The scanner can use the puzzle clues when checking available digits.

*Extreme*: The scanner can use global negative constraints when checking available digits.*Options*Depending on the scanning mode and the puzzle constraints, you can choose which types of clues can be used by the scanning algorithm.

*Scanning Speed*Control how fast the scanner runs.

The walkthrough is accessed by clicking the icon with the walking person below the controller. When playing a game, you can follow along in the modal, or you can press the button in the top right corner to open the walkthrough in a new tab. If you are creating your own puzzle the same modal can be used to create a walkthrough.

If you don't want to open the modal everytime you want to add a step, you can use the "w" shortcut, which will add the step for you. To add a description you still have to open the modal, though.

Okay

Info: We automatically save your walkthrough whenever you save your sudoku puzzle

Add step to walkthrough

19 can only be in two locations in row 3.

2, 7, and 8's location in r3 are restricted by the quads in box 2 and 3 and the thermo.

The digits on the thermo must be 4, 5. It cannot be 6 because of the 26 quad, and it cannot be 3 because the quads with 3 force 3 in box 3 to be in row 3.

1 cannot go anywhere on a thermo but the tip, restricting where 1 can go on the quads with 1.

Now the 9 in the quad is restricted to one location.

Each of the highlighted regions has a 6. This means the 6 in box 2 is restricted to one location.

The 1 in box 4 must be in c2, and the 1 in the 159 quad must also be in c2. There is only one place these two sets overlap, and so we can place a 1.

16 in c3 can only be in the quad, which means that the other 67 in the in the quad must be in c4.

An X-Wing of 1's is formed, forcing 1 in row 7 to be in box 8.

Make these pencil marks in preparation for the next step.

We know where 245 in the 245 quad have to be now.

And another X-Wing, this time on 6's. This forces 6 in row 7 to be in box 3, which leaves only one place for it to go.

Let's clean up some pencil markings. The red cells must contain a 5 and the green cell cannot contain a 3 since we know that 1 in c7 must go in box 9.

There are exactly 2 places for 3 to go in the 137 quad, both of which see the blue cell. Therefore, the blue cell is not a 3 and must be a 2.

The highlighted quads force 2 in c7 to be in box 6.

We can use sudoku to find another digit.

2 in c6 can only go in the green cells. 5 in c5 must go in the green cells to satisfy the quad. Therefore, we have a 25 pair.

Now there are only two places to place 13 to satisfy the 135 quad, which lets us place all the digits highlighted in blue.

3 in box 8 has to be in c5, pushing 3 up into the red cells, which forces the blue cells to be 589.

Do some Sudoku.

We know where 4 in the 245 quad goes now. Also, we can just place 3 on the thermo for free, so why not.

With the powers of thermos and quads forming pairs, we can make a couple of pencil notes (green squares) and get the blue squares.

Place 5 in the blue square to satisfy the quad. The green squares follow easily as a consequence of this new 5.

Filling in the 35 and 78 pairs in green, we can get some easy digits as long as we remember to consider the 1279 quad in box 3.

We must place 4 in the blue and not red cell for box 7 because if we put it in the red cell, there are not enough digits greater than 4 to complete the thermo with.

Use the thermo and do some more sudoku (we have a naked single in r2c1).

The blue cell is the only place 7 can go in r6, which makes the green digits cascade.