Sudoku

Digits 1–N, no repeats in a row, a column or a box

Rules

Fill every empty cell so that each row, each column and each outlined box holds every digit exactly once. Tap a cell, then tap a digit. The same digit again clears the cell.

Board sizes: 6×6 · 9×9
Difficulty: Easy · Medium · Hard · Expert
Daily set: yes, in rotation
Hints: named techniques