To save time, I needed a way to create a valid Sudoku puzzle of arbitrary size (square for now) without having to check whether or not there was a single solution. It turns out that it is possible to design a square Sudoku puzzle of arbitrary size. Even better if the puzzle requires singles strategies alone. Such puzzles have about 2/3 blanks.
Reducing the blanks to approximately 52%ish makes the puzzles have a unique solution. Filling in blanks that interlink make it possible to use singles strategies alone. At least, that’s what we find so far for all grids with a box dimension of 20 or less (400×400 grids). If you are interested in generating your own puzzles check out the following Sudoku puzzle creation strategy.
Can larger puzzles be created? It’s just a matter of memory, disk space and time. We’re also looking for different patterns that can be used to create valid Sudokus without having to check the puzzle every time. The largest Sudoku in the puzzle archive is box dimension 300 (90000×90000 grid). Larger Sudokus can be created but it would take a long time to download.