Minesweeper puzzles with no guessing: The Kid’s Treasure Map

Where minesweeper puzzles come from

The idea goes back to Mined-Out, a game by Ian Andrew for the ZX Spectrum in 1983. The version everyone knows is Microsoft’s Minesweeper, written by Robert Donner and Curt Johnson. It first came out in 1990, in the Windows Entertainment Pack, and then came with Windows for years.

Classic Minesweeper has a well-known flaw: the mines are scattered at random, so some boards can’t be finished without a guess. In 2000, a paper in The Mathematical Intelligencer proved that Minesweeper is NP-complete, which roughly means there’s no known shortcut for every big board. Puzzle makers answered with no-guess boards. Mines, in Simon Tatham’s free puzzle collection, makes every grid one you can work out from the first open space. And puzzle books print minesweeper as a pencil puzzle: every number is on the page from the start, and you mark where the mines must be. The Kid’s Treasure Map is that kind.

How The Kid’s Treasure Map plays

• Read the numbers. Each dug number counts the treasure in the 8 squares around it, corners too. The map says how many treasures there are in all.
• Plant the flags. Tap a square to plant a flag where treasure must be. Switch to Empty to ring a square you know is clear.
• Dig them up. Flag every treasure and the Kid digs them all up.

Puddles and the sandbox never hide treasure, and a dug square never does either. A number goes faint once it has that many flags around it, and turns red with a + if it has too many. Back one takes your last move back. On a keyboard, the arrow keys move between squares, Enter plants a flag, and O rings a square as empty.

A new map comes every day at midnight, your time, the same for everyone. Monday to Saturday the map is 8 × 8 squares, and Sunday’s is 8 across and 10 tall.

A worked example: the practice map

Every new player’s first map is a tiny practice one, 5 × 5, with a puddle in the top-right corner and two treasures to find. Eight squares are still grass: those are the only places treasure can be.

1. A 1 with one place to look. The 1 in the top-left corner touches three squares, and only one of them is still grass. Its treasure has to be there: plant a flag.
2. Full numbers clear their neighbors. The 1 in the middle of the top row touches that flag too, so it has its one treasure, and its other grass square, beside the puddle, is clear. The 0 below and to its right touches no treasure at all, so every grass square around it is clear: ring them.
3. The bottom row. The 0 in the bottom row clears the grass square beside it. Now the 1 above that square has only one grass square left that could hold its treasure. Plant the second flag.
4. Both found. The 1 at the end of that row now has its treasure, so the last grass square is clear. Two flags, and the map says two treasures. The Kid digs them up.

Each step asked the same question of one number: how many treasures does it still need, and how many places are left? Bigger maps work the same way, and on harder days two numbers side by side settle what neither could alone.

A pattern worth knowing: 1-2-1

Minesweeper players learn a few patterns by sight, and the 1-2-1 is the most useful. When three numbers in a row, 1, 2 and 1, sit under a straight row of hidden squares with nothing else hidden around them, the treasure sits over the two 1s, and the square over the 2 is clear.

Why: the 2 needs two of the three squares over it. If the middle one were a treasure, the 2’s other treasure would sit beside it, over one of the 1s, and that 1 would touch two treasures. So the middle is clear, and the 2’s two treasures sit on either side of it, over the 1s.

Tips for solving minesweeper puzzles

1. Start with the 0s. A 0 means no treasure around it at all: every square touching it is clear.
2. Count the places. If a number has exactly as many grass squares around it as treasures still to find, every one of them is treasure.
3. Take away what you’ve found. A 3 with two flags beside it is really a 1 now. Thinking of each number as “what it still needs” makes the next move easier to see.
4. Ring the rest. When a number has all its flags, ring its other squares clear. Their other numbers then have fewer places to look.
5. Compare neighbors. Two numbers that share squares tell you more together. If a 1 and a 2 share all but one of the 2’s squares, that last square is treasure.
6. Use the count. Near the end, the number of treasures left can settle the last few squares, even ones no number touches.

How it compares with Minesweeper

• Every number is on the map from the start. You don’t uncover squares, you mark them.
• There are no mines, only treasure, so a wrong flag never ends the game. You fix it and carry on.
• The map tells you how many treasures there are, and the count under it says how many you’ve flagged.
• Puddles and the sandbox are squares that never hide anything.
• There’s one map a day, the same for everyone, and never a guess.

If you like numbered squares that build a picture instead, try Grandma’s Knitting, our daily nonogram, and our guide to nonograms.

Why every map has exactly one answer

Each day’s map is made from the date by a program, so everyone gets the same one. The maker buries the treasure, then covers up dug numbers one at a time. After each one, a solver works the map out from the numbers alone, the way a careful player does: one number at a time, then two side by side, then the count, and on harder days a short “what if” you could follow in your head. A number stays covered only if the solver can still find every treasure. A map those rules finish has exactly one answer, and our tests also count every way the treasure could be buried, over months of maps, to be sure. How we make puzzles with exactly one answer explains how the family’s other dailies are checked.

Your result, par and the streak

Every map has a par time, about what the fastest third of players take. It shows while you play. Finish under par for a gold flag in your week. Your result shows your time, your streak, a flag for each day you dug, and what the Kid dug up.

Once the treasure is dug up it shows for a moment, then the yard goes back to plain grass, so a screenshot of your result doesn’t give the day’s map away. Share sends your map’s number and your time, never where the treasure was, with a link for a friend to try to beat your time. The Kid’s Treasure Map has its own board for your group and for the whole world, fastest first.

More daily puzzles from the Fibbersons

The Kid’s Treasure Map is one of the family’s free dailies. The others:

• Lie of Sight: a room seen from above, a family who each say what they saw, and one of them lying. About three minutes.
• Rex’s Fetch: lead Rex the dog through every square of the yard to the ball. See our guide to path puzzles.
• Lacey’s Web: spin a spider’s web back together from its numbered knots. See our Lacey’s Web guide.
• Grandma’s Knitting: knit what the numbers say, and a picture appears. See our guide to nonograms.

They’re all on the game picker, with the rules for each in How to play.

Questions people ask