Pippin
Also known as Star Battle and Two Not Touch
Place a penguin in every coloured region, with exactly one in each row and column. Penguins cannot touch, even at a corner, so each placement rules out nearby squares. Work through the regions until every penguin has a home.
How it works
- Place one penguin in every colour, row and column.
- No two penguins may touch, even at a corner.
- Tap to cross out a square, tap again for a penguin, and tap once more to clear it.
- Placing a penguin crosses out every square it rules out. A placement that breaks a rule is ringed in red.
Good if you want…
- Deduction without numbers or reading
- Working through coloured regions
- A gentle introduction to grid logic
How to solve Pippin
Follow the singles
A penguin rules out its row, its column, the rest of its colour and the eight squares around it, and the board crosses those out for you. After each placement, look for a colour, row or column with one open square left. Its penguin has nowhere else to go. Small colours run out of room first, so start there.
Singles rarely finish a board on their own. Every tier is dealt to need at least one of the steps below, even Easy.
Claim a line
When every open square of a colour sits in one row, that colour's penguin must be in that row. A row holds only one penguin, so every other square in it is out, whatever its colour. Columns work the same way. So does the reverse: if a row's open squares all belong to one colour, that colour's squares in other rows are out. Long, thin colours are the likeliest to do this.
Cross out squares that would starve a colour
You can rule a square out without placing anything. Imagine a penguin there and see what it would take away. If it would leave any colour, row or column with no open square, it cannot go there. A common case is a square touching every remaining square of a small colour. When a colour is down to two squares side by side, the squares directly above and below the pair touch both, so they are all out.
A two-by-two block is a handy special case. If a colour's open squares all fit inside one, its penguin will touch every other square of that block, so squares of other colours in it are out.
Share out rows in groups
A claim can span several lines. If the open squares of two colours all lie within the same two rows, those rows must hold those two penguins, one each, and everything else in both rows is out. Three colours packed into three rows work the same way, and so do columns. Turned round, two rows whose open squares belong to just two colours use those colours up, so their squares elsewhere are out.
Look for small colours crowded along the same stretch of rows or columns. Hard boards are dealt to need at least one group.
Test a square with a chain
Expert boards need a group or, sometimes, a chain. A chain is a test, not a guess. Suppose a penguin on one square and follow the singles, claims and groups it forces. If some colour, row or column ends up with nowhere to go, that square is wrong.
Test squares where a penguin would do the most damage, such as one beside two small colours. You can test on the board itself: place the penguin, follow it through, then Undo back to where you started, and its automatic crosses leave with it. A test that stalls without a contradiction proves nothing.
Common mistakes
- Trusting a penguin because it has no red ring. The ring only shows a clash with another penguin already placed, so a penguin on the wrong square can sit unringed for a long time.
- Drawing your own crosses around a penguin you are unsure of. The automatic crosses go when it goes, but yours stay, and one may cover the square the answer needs.
- Forgetting the corners. Penguins cannot touch diagonally, so penguins in neighbouring rows always sit at least two columns apart.
- Watching only the colours. A row or column with one open square left is just as forced.
Where Pippin comes from
Pippin follows the rules of the puzzle best known as Star Battle, credited to the Dutch puzzle designer Hans Eendebak and first seen at the 2003 World Puzzle Championship. Its classic boards ask for two stars in every row, column and outlined shape, the form the name Two Not Touch describes. Pippin uses the one-in-each version, with penguins for stars.
Pippin questions
How do the difficulty levels differ?
In board size and in the hardest step each board needs. Easy is 6 by 6 and asks for one to three claims. Medium is 7 by 7 and can ask for any number of them. Hard is 8 by 8 and needs at least one group. Expert is 9 by 9 and needs a group or a chain. A board always has as many colours as rows.
Is there a mistake limit?
No. Pippin does not count mistakes, and a round cannot be lost. A hint fixes mistakes before it adds anything: first it takes off a penguin on the wrong square, then it clears a cross you drew over a square the answer needs, and only then does it place a new penguin.
Is there a quicker way to mark squares?
Drag across the board to cross out several squares at once. A drag never touches a penguin, one that starts on a cross clears crosses instead, and the whole drag undoes as one step. On a computer, right-click a square to put a penguin straight on it or take one off.
Pippin in Winters Puzzles
Pippin is one of 40 puzzles in Winters Puzzles, so it sits alongside Patch, Logic Grid, Code Breaker 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 Pippin.
Free on iPhone and iPad, with 39 other puzzles alongside it. Or play it in your browser — no download, nothing to sign up for.
