Ripple
Also known as Colour Flood and Flood Fill
Your region starts in the top-left square. Recolour it to absorb touching squares of the same colour, then keep growing until it covers the whole board. Pip, the Winters Puzzles penguin, has measured the fewest moves for every board, so you can chase Pip's best or explore at your own pace.
How it works
- Grow the region from the top-left square until it fills the board.
- Tap a square or palette colour to recolour your region and absorb touching squares of that colour.
- Pip's best is the fewest moves this exact board can be solved in.
- Match Pip's best without hints for a Perfect result. Perfect it replays the same board so you can improve your route.
- Try colours freely. A longer route costs moves, never the round.
Good if you want…
- One simple rule and no reading
- Planning a short route through colours
- A quick puzzle measured in moves
How to solve Ripple
Know what a move takes
A move recolours your whole region, which then takes every patch of the new colour touching it, on every side at once. A colour that meets your edge in four separate places can take more than the biggest single block in view.
Let the controls do some of the reading. A swatch that would capture nothing is faded, and the colour you already hold is ringed. Tapping a square on the board plays that square's colour, but the square itself only joins if its patch touches your region.
Look one move past the biggest capture
Always taking the most squares will fill the board, but it often misses Pip's best on Easy and almost always misses it on Expert. What a move is really worth is what it leaves you touching. Three squares that open your edge onto a wide field of blue can do more than eight that end against a wall of small scraps.
So before you pick, picture the region after each colour on offer and ask what the following move could take in bulk. A thin patch that links your edge to a big one is worth far more than its size.
Stretch towards the far side
Your region pushes outward by at most one patch per move. Count the patches you would cross, by the shortest way, to reach the square farthest from you: you need at least that many more moves, however well you choose.
Give the region reach early. A line pushed across the middle touches far more of the board than a block tucked in the corner, and a long edge lets later moves take several patches at once.
Finish colours off
Every colour still showing outside your region, your own included, needs at least one more move. So a move that clears the last of a colour is usually worth taking: that colour never needs picking again.
The costly case is a colour split between two places. Coral beside your edge and coral in the far corner means choosing it twice, unless you wait until your region touches both. A stray square beside your edge, in a colour you will play again anyway, costs nothing.
Check yourself against Pip's best
Pip's best, named for the Winters Puzzles penguin, is exact: the search that measured the board proved no shorter route exists. It also makes a running check. Add your moves so far to the colours still showing outside your region, and if that is already above Pip's best, this attempt cannot be Perfect.
Then reach for Reset, not Undo. Undo restores your last region but still adds one to the count, while Reset puts the board back as it was dealt with the count at zero. There is no move limit and no way to lose, so a first attempt spent scouting the route is not wasted.
Common mistakes
- Tapping a distant square to claim it. A tap plays that square's colour, and only squares of that colour touching your region join.
- Undoing your way back while chasing Pip's best. Each undo adds a move, so starting again with Reset is cheaper.
- Taking the biggest capture every turn without looking one move further.
- Leaving one colour stranded in two corners, which costs a separate pick for each.
Where Ripple comes from
Colour-flood games play like flood fill, the routine behind the paint-bucket tool in drawing programs, which repaints a connected area of one colour in another. Computer scientists have shown that finding the fewest moves on boards like these is NP-hard once three or more colours are in play, so no known method does it quickly for every board. Ripple settles each one with a search when it is dealt.
Ripple questions
Can I beat Pip's best?
No. The search run when a board is dealt proves nothing shorter exists, and a board it cannot settle is thrown away. Match Pip's best without a hint and the round is Perfect. In free play, finishing above it offers Perfect it, which deals the same board again.
How do the difficulties differ?
Easy is a seven-by-seven board in four colours, with Pip's best at 8 to 11 moves. Medium grows to eight-by-eight and adds a fifth colour, for 10 to 14. Hard is nine-by-nine at 12 to 15, and Expert is ten-by-ten at 13 to 17. The palette stops at five colours; the boards grow instead.
What does a hint do?
It plays one colour for you: the next move on a shortest route from where your region is now, not from the start. It counts as a move like any other, so it cannot win back moves already spent, and a round that used one is not counted as Perfect.
Ripple in Winters Puzzles
Ripple is one of 40 puzzles in Winters Puzzles, so it sits alongside Tessera, Flow, Shift and everything else in the app rather than being a download of its own. It counts towards your stats and streak like any other puzzle. It also has a published board in Pip’s dailies, with earlier dates available in the archive.
Play Ripple.
Free on iPhone and iPad, with 39 other puzzles alongside it. Or play it in your browser — no download, nothing to sign up for.
