Notes on this puzzle
Sudoku #5412 is an expert grid with 26 givens, which leaves 55 cells waiting for a digit. Played purely by logic, it takes 58 forced steps from the first placement to the last.
Most cells fall to the hidden single move: 51 of the 58 steps. Single candidate accounts for 4 more. The toughest moment needs XY-Wing, and that single step is what sets the level.
Among the givens, 7 is the most common digit (5 times) and 2 the rarest (2). The emptiest box is the top-middle one, with 2 givens; the top-left box is the most crowded, with 5.
Where to beginLook at row 3, column 2 first: a hidden single is available there from the very start. Expect a stage where only a pattern across several lines moves the grid on; full notes make it visible.