How to play
Fill every white cell with a digit from 1 to 9. A clue in a dark cell gives the sum of the run of white cells to its right (the upper number) or below it (the lower number).
A digit cannot repeat within a run. The same digit may appear again in the same row of the grid, as long as it belongs to a different run.
Every puzzle has a unique solution. Tap a cell and use the pad; notes work exactly as in sudoku.
Strategy and tips
- Begin with the runs that have a single combination. In two cells, 3 is 1+2, 4 is 1+3, 16 is 7+9 and 17 is 8+9. In three cells, 6 is 1+2+3, 7 is 1+2+4, 23 is 6+8+9 and 24 is 7+8+9. The full table covers runs of up to nine cells.
- Where two runs cross, the shared cell must be a digit that both runs can use. A two-cell 4 (1 and 3) crossing a two-cell 3 (1 and 2) can only meet at 1.
- Think about the missing digit. Eight cells adding to 41 use every digit except 4, because 45 − 41 = 4. Seven cells adding to 38 leave out two digits that add up to 7.
- Check the high and low ends. A two-cell 15 can only be 6+9 or 7+8, so it never contains a digit from 1 to 5.
- From medium size up, a few runs can only be settled by testing which combinations still fit the crossing runs at the same time. Notes make this manageable.
- Fill the two-cell runs early. They have the fewest combinations, and once one digit of a pair is known, its partner follows from the sum — which then feeds the crossing run.
Questions
- What do the sizes mean?
- Easy is a 6×6 field with runs of up to 4 cells, solvable with combinations alone. Medium is 8×8 with runs up to 5, hard 10×10 with runs up to 6, and expert 11×11 with runs up to 7, where you sometimes need to test whether a combination fits the crossing runs.
- Can a digit repeat in a row of the grid?
- Yes, as long as the two cells are in different runs. The no-repeat rule applies to each run, not to the whole row or column.
- Why is 0 never used?
- Only the digits 1 to 9 are allowed. That keeps the list of combinations short enough to learn, and it is what makes the deductions possible.
- Do numbered sheets load instantly?
- Yes, they are prepared in advance. A new free game is built on your device, which for the larger sizes can take a second or two on an older phone.