MaaTec Sudoku Mobile 1.60
the author of this app says:
Sudoku game and solver for Windows Mobile with great graphics. Sudokus with 4x4, 5x5, 6x6, 7x7, 8x8, 9x9, 10x10, and 12x12 cells are possible (plus 16x16 on VGA PDAs). Let the application generate sudokus in different difficulties or enter and solve your own ones. Several graphic boards for QVGA and VGA displays are included. You can use various hint functions while playing.