SudokuUI

To run the file type SudokuUI at the command line, this will bring up a figure window with the layout for a standard blank 9x9 sudoku grid on it. Right clicking on any of the blank squares will then provide you with the available numbers that can be entered into the box, right clicking on an occupied box will then colour all the inadmissable cells for this number red, leaving leaving the rest white.
Control+Z will undo choices, Control+C turns on a simple checking mode where squares which have only one option available to them or numbers which can only go in one place in a row, column or submatrix are filled in.

SudokuUI(16) opens up a solving assistant for 16x16 grids using the numbers 0-9 and characters A-F.