How to play Ripple
Ripple gives you a grid of numbers and hides a handful of sources inside it. Every number is a distance. Find the sources, and the board is done.
The rules
- The grid contains exactly K sources. Their positions are not marked.
- Every number printed on the board is the Manhattan distance from that cell to the nearest source — counted in up/down/left/right steps, never diagonally.
- Mark all K sources. The board checks itself the moment the last one is placed.
- Each puzzle has exactly one solution, and it can always be reached by deduction.
A worked first solve
Take a 6×6 board with three sources. Suppose the clues include a 0, a 1 and a 4.
Step one — the 0. A cell is at distance zero only from itself, so that cell is a source. You now have one of the three.
Step two — the 1. A clue of 1 must have a source exactly one step away: directly above, below, left or right — never diagonal. That is four candidate cells, which is not yet an answer. But every cell within distance 0 of that clue is ruled out, and each clue you process removes candidates from the whole board.
Step three — the big numbers. A clue of 4 rules out every cell within three steps as a source. On a 6×6 board that is most of the region around it. When two big clues overlap, the remaining candidates collapse fast — often to a single cell, and then that cell must be a source.
That is the whole game: each clue eliminates a diamond of cells, and when only one candidate survives in a neighbourhood, it becomes a source. Repeat until the count is reached.
Why you never have to guess
Boards are not filtered by testing random guesses. Each one is generated by placing sources, then removing clues one at a time, keeping a clue only if the board stays solvable by pure propagation. The generator stops at the smallest set that still works, then adds a few harmless extra clues for texture.
The practical consequence: if you are stuck, you have not yet found the weakest clue on the board — not run out of information.
The three things to look for
- Zeros. Free sources. Take them first.
- Ones at the edge. A 1 in a corner has only two possible neighbours, not four.
- Numerical counting. If you have already placed K−1 sources, every remaining marked cell is ruled out, which often finishes the board on its own.
These are expanded in the strategy guide.
Difficulty
Three sizes: 6×6 with 3 sources, 8×8 with 4, and 10×10 with 5. The larger boards do not change the rules — they simply give you more clue overlaps to work with, and more places to be wrong.
Frequently asked
Is Ripple like Sudoku?
Only in spirit. Both are pure-deduction grid puzzles with one solution. Sudoku constrains rows and boxes; Ripple constrains distances, so the reasoning is geometric rather than set-based. If you like the sudoku variants here, Ripple is a different shape of the same pleasure.
What happens if I place a wrong source?
The board shakes and clears your marks. There is no penalty beyond the timer — the point is the deduction, not a score.
Can I get a hint?
Yes. The hint button reveals one real source. It is there for the moment you want to check a deduction, not to finish the board for you.
Play Ripple ↗