Sudoku

SUDOKU RULES:

• All rows, columns & blocks must be filled in with numbers.
• A 'block' is a square of numbers (3x3 cells for the 9x9 sized Sudoku), showed in alternating color.
• No repeated numbers are allowed in a row, column, or block.

TIP:

• The generation algorithm of these Sudoku boards ensures they all have a unique solution, there is only one correct position of a number in each row, column & block.
  
• The game allows you to fill in the incorrect numbers, only fill numbers in cell when certain that they must be there.
• Use the undo function to undo filling in cells.

CONTROLS:

• Click small number in Cell to fill it.
• Undo: Z
• Redo: Y

OPTIONS:

• Seed - If empty a random Sudoku is generated.
  Identical Sudokus are generated from the same seed.
• Size: 4x4, 9x9, 16x16.
  Difficulty options are limited to Easy for 16x16 due to generation of more difficult ones takes exponentially longer.
• Show All Candidates - Shows only the valid options for numbers in cells (if no valid option are available for a cell - some other cell has been filled incorrectly, use undo).
• Dark Mode: Inverts the colors.