There are many applications that allow you to play, but they don't allow the same degree of customisation SudoSolve does.
The board is too big? you can easily change it's size. Don't like the color choice? You can change it! SudoSolve support very intuitive theme changing.
If you think so, you can easily change the board size to 16x16, 25x25 or even 36X36. The grid can also get smaller if you want it to.
Enjoy the game here!