Sudoku exploded on the world back in 2005.

In May that year, Andrew Stuart started his first Sudoku ‘solver’ – thinking he could solve any Sudoku trivially with a little programming and a few tricks.

What he, and the solving community, quickly found out was that Sudoku had immense depth and there were many Sudoku puzzles that couldn’t be solved logically.

Since then, over fifty different strategies have been discovered – and all these go into the making and grading of the puzzle.

Such understanding is necessary to exploit the full spectrum of possible Sudoku puzzles and provide the different grades you see here on this player.

All puzzles have been tested for a single solution and for logical methods of solving – although this might be obscure on the hardest puzzles to say the least.

These are some of the highest quality Sudoku you will find anywhere. Best of luck solving...