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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

Note that the sum of the 23 cages plus the red cell minus the green cell must equal 45, since each box's digits add to 45.

This means that 46 + r - g = 45, or g = r + 1. This means the green cell must be a 6 or an 8.

Now, we push the same idea a little bit farther: 46 + g + y - b = 45, or b = g+y+1. If g=8, then b is at least 10, which is not possible, so we actually know that g=6.

Also, we get y=12 and b=89.

Since we know the red digit is one less than the green digit, we can fill in a 5.

We need 689 in row 4. At most one of these can go in box 6 and at most one of these can go in the 23 cage that extends down into box 4 (since otherwise the sum is at least 1+2+3+4+6+8=24). Therefore, the purple cell must be 689.

The purple cell must be 6 because the purple and blue cell cannot be the same. If the purple cell is (say) 8, then it forces 9 into the cage in box 6, which makes the blue cell 8. The same problem occurs if the purple cell is 9.

9 cannot go into a 23 cage of size 6, since 1+2+3+4+5+9=24. Thus 9 in row 4 must go in box 6, and we can fill out a couple more digits.

Go back to step 2: we can now determine the yellow cell.

Now the 23 cage with the blue cell must be 2+4+8+9. Now we can fill in a lot of stuff...

Where in box 7 does 9 appear? Not in the 6 cell 23 cage. But 8 and 9 cannot appear together in the 5-cell 23 cage either so we can place an 8 in box 7.

Fill out a couple more things...

Where in box 7 can 7 appear? Not with the 6-cell 23 cage, we know that 8 must be accompanied by 12345. And not with the 23 cage, since we know that 5+6+7+9=27 which is way too big.

Look at box 7: 45-23-8-7=7. Therefore r89c3 must add to 7, the only way to do this is 3+4.

A bit of cleanup...

In a 6-cell 23 cage without 8, the digits must be 123467 (try it yourself).

Based on the geometry of the cage, the gray cell in box 3 must be the same as the gray cell in box 2, that is the only place it can go. This rules out 1 as a possibility and thus the gray cells are 6.

Do some sudoku.

Note that in box 8, 45 = 8 + b + 23 - r, rearranging to b = 14 + r. This means that b is at least 15, meaning the smallest digit which can appear in the blue cells is 6. This forces 4 into the 23 cage.

(We've ran out of colors so I've deleted old ones.)

However, since we need a 6 in c5, the largest possible sum that the blue cells can give us is 15 from 6+9. So we know the blue cells, and the red cell.

Do a lot of sudoku.

The yellow cell must be 2 because if 2 was in the 23 cage along with 6, then the other two digits would have to add to 15. The only pairs that add to 15 are 6+9 and 7+8, neither of which would be possible.

Similarly the green cell must be 7 because if 7 was in the 23 cage with 6, then the other two digits would have to add up to 10. Since we have 1, 2, 7, 6 already, none of the pairs that add to 10 are possible.

The purple cell is 4 because 45-23-8-1-2-7=4.

And now you have finished the puzzle. Congratulations! Thank you for solving, and I hope you enjoyed :)

Killer cages: The digits in each cage must sum to 23 and digits in a cage must not repeat. Classic sudoku: Place the digits 1-9 in the grid such that each row, column, and region has one copy of each digit.

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