Notes on this puzzle
28 digits are printed in this grid and the other 53 cells are yours to fill. A solver that never guesses gets through it in 54 steps.
Most cells fall to the hidden single move: 52 of the 54 steps. Box–line reduction accounts for 1 more.
Among the givens, 3 is the most common digit (4 times) and 2 the rarest (2). The emptiest box is the central one, with 2 givens; the top-left box is the most crowded, with 4.
Where to beginLook at row 1, column 6 first: a hidden single is available there from the very start. Pencil in candidates for one box at a time and watch for two cells that share the same pair.