Each row, column, and 3×3 box must contain the digits 1–9 exactly once. Tap a cell, then tap a number to place it.

Every correct placement grows your combo and climbs a musical scale. Chain placements for maximum dopamine. A wrong guess resets it to zero.

Toggle notes mode to pencil in candidates. Notes auto-clear from neighbors when you confirm a correct number.

One free hint per game reveals a correct cell. You get three mistakes before it's game over, so choose wisely.