Sudoku Help provides puzzles for you but it also enables you to enter a puzzle of your own. Pencilmarks are generated automatically, and you can show or hide them as you like. You can request a hint for the next step. For this app, both landscape and portrait orientations are supported.
For those who are unfamiliar with Sudoku:
All digits 1, 2, ..., 9 must occur
- in each of the nine (horizontal) rows
- in each of the nine (vertical) columns
- in each of the nine 3 x 3 subgrids (separated by thick lines)
