Pencil Mines is a mine-clearing logic puzzle drawn on squared paper. Somewhere under the shaded squares are hidden mines. Every square you open either shows a number, telling you how many mines touch it, or opens a whole empty area at once. Use the numbers to work out where the mines are, mark them with flags, and open every other square without setting one off. Your first square is always safe, and with No guessing turned on, every board can be cleared by careful reasoning alone.
Pencil Mines rules
- The board is a grid of hidden squares. A set number of them hold mines: 10 on Easy, 22 on Medium and 40 on Hard.
- Open a square to see what is under it. If it is a mine, the game is over.
- A safe square shows how many of the eight squares around it hold mines, counting diagonals. A square with no mines around it shows nothing, and opens its neighbors for you.
- You can mark a square you are sure holds a mine with a flag. Flags are notes for you: they never count as moves, and you can take them off again.
- You win when every square without a mine is open. You do not need to flag the mines to win.
- The first square you open is never a mine, and nor are the squares around it, so the game always starts with an open area to read.
How to play on this page
- Choose Easy (8 × 10), Medium (10 × 13) or Hard (12 × 16), then tap or click any square to start. The timer starts with your first square.
- On a computer, click to open a square and right-click to put a flag on it or take it off.
- On a phone or tablet, tap to open a square and press and hold to place a flag. If you prefer, switch the tool under the board from Reveal to Flag, so that every tap places a flag.
- Tap or click a number that already has that many flags around it to open all the other squares around it at once. Make sure your flags are right first: a wrong flag means a mine goes off.
- The counter next to the timer shows how many mines are still not flagged. Pause hides the board and stops the clock.
- With a keyboard, the arrow keys move between squares, Space or Enter opens, F flags and P pauses.
- Your game in progress, your options and your best times are saved in this browser, so you can close the page and come back to the same board.
The No guessing option
On a board made purely at random, you sometimes reach a point where two squares are equally likely to hide the mine, and no amount of thinking can tell you which. You have to guess, and half the time you lose.
With No guessing on, which it is unless you turn it off, the page only gives you boards that a built-in solver can clear from your first square using logic alone. The solver reads the numbers the way a careful player does: one number at a time, then pairs of numbers that share squares, then the count of mines left. If it ever has to guess, the board is thrown away and another is drawn. So whenever you are stuck on one of these boards, there is always a square you can prove is safe somewhere.
Turning the option off gives you the traditional random boards. Changing it during a game applies from your next board, and best times count either way.
Tips for clearing the field
- Start with the easy numbers. A 1 that touches only one hidden square has found its mine. A number that already has all its mines flagged makes every other square around it safe.
- Look for the 1-2-1 pattern along a straight edge of open squares: the mines are in the hidden squares directly across from the 1s, and the one across from the 2 is safe. In a 1-2-2-1, the mines are the two squares across from the 2s.
- Compare neighboring numbers. If a 1 touches two hidden squares and a 2 next to it touches those two plus one more, that extra square must be a mine.
- Corners and edges give you fewer squares to think about, so the numbers there are often the quickest to settle.
- Near the end, count the mines left. If the counter says one mine remains and only one place can fit it, every other hidden square is safe.
- Speed comes from revealing around numbers. Once a number has its flags, one tap opens everything else around it.
Frequently asked questions
- What kind of game is Pencil Mines?
- It is a mine-clearing logic puzzle, a kind of game that has been around on computers for decades in many versions. Pencil Mines is our own take on it, drawn like pencil on squared paper, with boards sized for phones and an option that removes guessing.
- Is the first square always safe?
- Yes. The mines are only placed after your first tap, and never on that square or the eight around it. That is why the first square always opens an empty area to start from.
- What does No guessing mean?
- Every board made with this option can be cleared from your first square by reasoning alone. A solver plays each board before you see it, and only keeps the ones it finishes without guessing. On boards made without the option, you may sometimes have to take a chance.
- Why did a mine go off when I tapped a number?
- Tapping a number that has as many flags around it as it shows opens every other square around it. If one of those flags was in the wrong place, one of the opened squares held the real mine. After the game the board shows wrongly placed flags with a cross.
- How do I place a flag on a phone without opening the square?
- Press and hold the square for a moment until the flag appears, or switch the tool under the board to Flag so that taps place flags. Holding never opens the page’s menu or selects text.
- How are best times counted?
- Each level keeps its own best time, measured from your first square to your last. Paused time and time while the tab is in the background are not counted. Setup also shows how many games you have won on each level.
- Do I need an account?
- No. Everything works without signing in. Your game and best times are saved in this browser only, so clearing your browsing data or switching devices starts you fresh.