Campfires

The meadow is a square grid, cut into patches of tent cloth — the camps. There are as many camps as rows. Light exactly one campfire in every row, in every column and in every camp, and keep the fires apart: no two may touch, not along a side and not at a corner, or the sparks would jump. That is the whole of it. When the last fire is lit with nothing in conflict, the board is solved.

Every board has exactly one answer, proved by two separate solvers before you ever see it, and none of them asks you to guess. If you are stuck, there is a deduction you have not found yet — never a coin toss you have to take.

Ash and fire

Tap a square once to mark it with ash — a small cross that means "no fire here". Tap it again to light a fire, and a third time to clear it. Drag across empty squares to ash a run of them at once. With Auto-ash on, lighting a fire ashes everything it rules out — its row, its column, its camp and the eight squares around it — and lifting the fire lifts that ash again. It is on by default for Easy and Medium and off for Hard. A fire that breaks a rule glows; free play can hide that if you would rather find your own mistakes.

The Daily

Every day there are three new boards — an Easy, a Medium and a Hard — the same three for everybody in the world, turning over at midnight UTC. Each is a race against the clock: five minutes for the Easy, ten for the Medium, twenty for the Hard, counting down while you play and stopping whenever you step away (the meadow is covered while it's paused). Solve it in time and your time goes on the leaderboard; if the clock reaches zero, that board is a miss for the day and your streak starts again tomorrow. There are no hints on the Daily, and a conflict always shows. Free play has no clock to beat and three hints a board.

How the levels are graded

Difficulty is not the size of the meadow alone. Each board is solved first by a program that works the way a person does — cheapest deduction first — and the hardest deduction it needs is the board's level.

• Easy (6×6) falls to singles: a camp drawn entirely along one row owns that row's fire, and a row, column or camp with one square left must have its fire there.
• Medium (8×8) needs confinement: a camp whose open squares all lie in one row clears the rest of that row, and a square whose fire would ash every open square of some other camp can't be a fire.
• Hard (10×10) needs pairs and short chains: two camps confined to the same two rows own both of those rows' fires, and "if a fire went here, that camp would have nowhere left" — found within three moves.

A few habits that help

• Start with the small camps. A camp of two or three squares has few places for its fire, and whatever they share, it rules out.
• Look for straight camps. A camp lying along one row or column owns that line's fire — ash the rest of the line at once.
• Ash generously. Most of a solve is ruling squares out. The fires tend to place themselves once enough of the meadow is grey.
• Count camps against rows. If two camps both fit inside the same two rows, those two rows' fires are theirs, and every other camp's squares in those rows are ash.

Where it comes from

Campfires belongs to the Star Battle family of placement puzzles, a staple of puzzle magazines and championships: stars instead of fires and regions instead of camps, with one star per row, column and region and no two touching. This is the one-star kind, the simplest and quickest — dressed for an evening by the fire.

The rules in full, the deductions each level needs, the skins and the badges are in the Campfires guide.