Sudoku

1. 1Fill the grid so that every row, every column and every 3 by 3 box holds the digits 1 to 9 exactly once. Every puzzle has exactly one solution: you never have to guess.
2. 2Touch a square, then a digit. With a keyboard, move with the arrows and type the digit.
3. 3Not sure yet? Turn on Notes to pencil in the digits a square could still take.
4. 4Check my work marks the digits that are wrong. A hint fills in one square: it costs a little XP, never time.
5. 5There is a new puzzle every day, the same for everyone: easy on Monday and Tuesday, medium on Wednesday and Thursday, hard from Friday to Sunday. The timer is optional.

Keyboard: arrows to move, 1 to 9 to write, N for notes, Backspace to erase, U to undo.