The Big Sudoku

Samurai Sudoku and 16x16 'Super' Sudoku. For those that want a puzzle that lasts more than a few minutes. And now an unlimited supply of automatically generated 9 x 9 Sudokus for when you want a quick puzzle.
The Samurai and Super Sudokus come in three levels of difficulty, none of them are trivial or easy. These are Sudoku that will take a bit of time to solve. And if you complete one you will have solved it. There are no cheats or hints to allow you to carry on if you get stuck. The 9x9 Sudoku come in four levels of difficulty with the most difficult requiring slightly harder solving techniques than the larger puzzles.
There are aids to help with some of the legwork though, the Sudoku will auto fill and update pencil marks showing all of the possible numbers available in each square and you can highlight all squares that can hold a possible number allowing patterns to be seen. But, there is nothing in the Sudoku to shortcut the mental process required to complete it.
The list of Sudoku now shows whether automatic pencil marks or number highlighting have been used and the best time for each Sudoku will reflect this, if you complete a Sudoku without using assistance this will be recorded as your best even if it was slower than a previous attempt where assistance was used.
The Sudoku auto save so you can have several on the go at any time.
Also for traditionalists or the masochistic you can email a Sudoku to your computer to be printed out and solved the hard way with no highlighting assistance using a pen and paper.
Because of the size of the Sudoku this app will work best on a tablet or large screen phone. However, the grid can be zoomed so play on almost any device should be possible with a pit of patience.