At the start of the puzzle, take a good look at the shape of the jigsaw regions, and see if you can spot any jigsaw regions that share many of their squares with a row or column as this can often bear fruit quickly by reducing possible locations for any of its givens in that shared region.
What is Sudoku Evil? Sudoku evil is a 99 grid sudoku puzzle with the highest possible level of difficulty. It's an advanced level only for experienced sudoku solvers.
