It differs in that it introduces numbers surrounding the grid - each number is the sum of the three nearest digits in that row or column.

For example, in the puzzle to the right, the three cells shaded grey must add up to 21 and those shaded yellow must sum 6.

- Click the "Menu" button, then select the "New Puzzle" menu item and select a difficulty level from the dropdown menu.
- Fill in blanks with the Pen (select a cell, then click on the number you want to enter).
- If you're not 100% sure of a number, you can make a note of it in the cell using the Pencil. To do this, click the "Pencil" icon to be placed in "Pencil mode".
- You may enter as many pencil marks as you like in each cell.
- To change back to "Pen" mode, click the "Pen" icon. You can also switch between pen and pencil modes quickly by pressing the "P" key or by using the mouse wheel. (See tips below.)

- Use the arrow keys to navigate around the grid.
- Use the number keys to enter a number in the highlighted cell.
- Press the space or Delete key to remove any numbers from the highlighted cell.
- Press the "P" key to toggle between Pen and Pencil or use the mouse wheel.
- Press the "U" key to undo last input.
- Press the "C" key to change all cells with one possible (pencil mark) to pen.
- Hold
**Shift**key down to always enter in pencil (not operable with the number pad).

- Clicking a frame number will show all the possible 3 digit combinations that sum to that number.
- Click the Undo icon (yellow arrow) to undo last input. You can undo all the way back to the beginning.
- Holding the
**Shift**key when clicking on a number in the input panel will pencil that number in. You may find this more convenient than toggling between the Pen and Pencil icons. - To remove just one pencilled number in a cell, enter that number again.
- To remove all pencil numbers in a cell, either click the eraser button or simply "pen" the final choice in.
- To remove all pencil marks from all cells, use the menu option under "Edit".
- There is an alternate mode of number input via the mouse called "Active Number Mode" (see below).

To change the active number, select a new one from the Number Pad or scroll the mouse wheel down/up to increase/decrease the number. (If not in Active Number Mode, the mouse wheel will toggle between pen and pencil.)

In the Active Number mode, all pencil functionality remains the same as does the ability to use the keyboard.

The first three options will generate a puzzle at three different difficulty levels.

The first two levels - Easy and Medium - will generate new puzzle every minute.

The third level - Hard - will generate a new puzzle every hour.

Note: All puzzles are **solvable by pure logic** - no guessing required!

If the only way to solve a cell is via more advanced solving techniques (as found in Hard and Tough puzzles), then the clue will point you to the cell and say what technique(s) is/are required. This is not as helpful and you may need to resort to the "Solve One Cell" if still stuck.

For an explanation of these strategies, please consult the online tutorials found in the "classic" Sudoku.

**Active Number Mode:** This toggle Active Number Mode, described above.

**Show Timer:** Toggles display of timer.

**Show Pen/Pencil Cursor:** Toggles whether the pen/pencil cursor is displayed over the grid or just the standard finger cursor. (Does not apply if Active Number Mode set.)

**Auto Show Errors:** If checked, as you enter a number in a cell, it will display in red if incorrect.

**Auto Remove Pencil marks:** If checked, when you enter a final (pen) number in a cell, that number will be automatically removed from the possibles in all other cells in same row, column or block.

**Sound Effects:** Toggles sound on/off.

**When Select Num Show All Its Cells:** If checked, when you click on a number on the Number Panel, it will highlight all
the cells that contain that number. (Does not include pencil numbers.)

**De-emphasize Completed Numbers:** If checked, when all 9 of a number have been entered **correctly**, that number
will be de-emphasized on the Number Panel. You can still select the number, though.

You can also customize the color of the grid and the numbers.