Goal: Fill every cell with digits 1-9 so each row, column, and 3x3 box contains every digit exactly once.
Cages: Dotted-line groups show a target sum. All digits in a cage must sum to that number, with no repeated digits inside the cage.
45 Rule: Each row, column, and 3x3 box sums to 45 (1+2+...+9). Use this to find cells outside cages.
Controls: Tap a cell to select, then tap a number. Toggle Notes mode to pencil in candidates. Use Undo to reverse moves, Hint to reveal a cell, Combos to see valid cage combinations.
Mistakes: 3 wrong placements and the game is over. Wrong entries highlight in red.