The goal is to enter a digit into every cell so that each row, column, and the
nine 3x3 blocks, each contain all of the digits, from 1 to 9, exactly once. For information
on specific strategies see the tutorial or Sudopedia.

Input Modes - There are three input modes available. They are described lower
down in the settings section. Here is a quick description that covers the default setting,
which is hybrid input.

Entering digits - First, tap the digit button for the digit you want to enter. The
digit buttons are at the bottom of the board. When tapped, the digit button will turn green to
show that it is selected. Then, tap a blank cell to enter the selected digit into that cell. If
the digit button does not turn green, tap the green cell to deselect it and then tap the
desired digit.

Clearing Mistakes - To clear an already entered digit, tap the Erase button. It will
turn green to show that it is selected. Then, tap the cell you want to clear.

Pencil Marks - Tap the pencil button to turn on pencil marks mode. The pencil
button will turn green to show that pencil mark mode is on. Then tap on a cell to place a
pencil mark for the selected digit in that cell, or remove the pencil mark if there is
one already. You can tap the pencil button again to turn off pencil mark mode.

To enter several pencil marks into a single cell more quickly, tap the green digit button
to deselect it. Then tap a cell, which will turn green to show that it is selected. If the
pencil button is not green, tap it so that it turns green. You can now tap digits to turn the
corresponding pencil marks on and off in the selected cell.

Hint - tapping the Hint button and then selecting Hint from the list will give you a
hint about how to proceed from the current board position. When a hint is displayed, tapping on the hint text will move to the next page or return to play. Using hints adds extra time to the play clock. More time is added for hints
about more difficult techniques.

Undo/Redo - tapping the Undo button undoes the most recent change you made to the board.
Once you tap the Undo button, the Redo button will appear. You can undo and redo moves back to the
start of the game.

Solve - tap the Hint button, and then select Show Solution to show the solution to the
current puzzle. Any digits you have not yet entered will be shown as pencil marks. Using Show Solution
will add a substantial amount of time to the game clock.

Fill in Pencil Marks - tap the Hint button, and then select Fill in Pencil Marks to fill in
all of the pencil marks based on the current board position.

Pause - returning to the Main Menu while playing pauses the time clock. The time clock
only runs when the board is displayed. If you take a call, exit Sudoku Joy, or lock the iPhone,
the time clock also pauses.

Play Sounds - When on, any time you enter or remove a digit or pencil mark on the
board there will be a click sound.

Don't Sleep - When turned on, the screen will not dim and the phone will not go to sleep
while Sudoku Joy is running, unless you manually put it to sleep.

Show Time Clock - Offers three possible settings. "Never Show Time" never displays the
time or how your time compares to others. "Show Time At End" shows the time only when the game is
complete. "Always Show Time" displays the minutes and seconds elapsed at the bottom of the board.

Highlight - When on, all of the cells that contain the current digit are highlighted in
yellow. All of the cells that contain a pencil mark for the current digit are highlighted in pink.

Blink Completed - When on, any time you complete a house that house will blink yellow
and when you complete a digit all of that digit will blink green.

Digit Font - Allows you to select which font should be used for displaying digits.

Pencil Marks - Offers a choice of four display styles for pencil marks: variable size
small digits in a
3x3 grid, squares, and circles.

Skin - Offers a choice of five color schemes used to display the playing field.

Mark Mistakes - Offers three possible settings. "Don't Mark Mistakes" will not mark
anything. "Mark Illogical Digits" will show any digit which violate the one rule (two or more
of the same digit in the same row, column, or block) in red. "Mark Incorrect Digits" will show
any digit that is not part of the correct solution to the puzzle in red. "Mark Incorrect Digits"
can be used as a hint, so time may be added to the clock when a cell is marked as incorrect.
The amount of time added depends on the difficulty level.

Input - Offers three possible settings. "Digit Then Cell", select a digit and then
click on cells to enter that digit into the cells. "Cell Then Digit", select a cell and then
click on a digit to enter that digit into the cell. "Hybrid", allows you to switch between
the other two modes as needed. If you click on a cell first you are temporarily in cell then
digit mode. If you click on a digit first you are temporarily in digit then cell mode. If you
click on whatever is highlighted in green (a cell or a digit), so nothing is highlighted, your
next touch selects a new temporary input mode.

In "Digit Then Cell" mode, to enter several pencil marks into a single cell more quickly,
tap the pencil button twice quickly. The pencil button will turn yellow to show that rapid pencil
mark mode is on. Then tap on a cell to select that cell. The cell will turn green to show that
it is the selected cell. You can then tap the digit buttons to turn the corresponding pencil
marks on or off in the selected cell.