How to Play Minesweeper: Rules, Difficulty & Chording

Q: What does NG mean in Minesweeper?

NG stands for no-guess. An NG board can be cleared from start to finish by logic alone. Every mine can be worked out from numbers you’ve already opened, with the mine counter settling the last few if needed. You never reach a 50/50 where the only move is to pick a tile and hope. So a loss always comes down to a misread, never to luck. RetroSweep daily boards from September 27, 2026 on are built to be no-guess. When a daily board is generated, a solver plays it from the start tile. Any layout it can’t finish without guessing is thrown out for the next one. A board that passes carries an NG tag in its title strip. Classic boards are random, like the original Windows game, so they can still end in a guess.

Q: What does NF mean in Minesweeper?

NF stands for no flags. An NF win is a board cleared without placing a single flag. Instead of marking the mines, you open only the safe tiles and leave the mines alone. Flags are optional, because a board counts as cleared the moment every safe tile is open. Many fast players skip flagging entirely, since it saves clicks. RetroSweep marks NF wins with an NF badge on the win screen and next to the player’s name on the daily leaderboards. It’s a style marker, not a separate ranking. NF and flagged times rank together, fastest first. The badge is just for bragging rights.

The rules

The board hides a fixed number of mines. Reveal every tile that is not a mine and you win. Reveal a mine and the game ends.

Each revealed number tells you how many mines touch that tile, counting all eight neighbors, diagonals included. That’s how you work out which neighbors are safe (more on the numbers).

In Classic mode, your first dig is always safe. The mines are placed after your first click. We’re not monsters.

Left-click a tile to reveal it.
Right-click a tile to cycle its mark: flag → question mark → clear.
Click a revealed number to chord (see below).

Difficulty levels

Pick a preset from the toolbar, or set your own width, height, and mine count with Custom:

Level	Grid	Mines	Density
Beginner	9×9	10	12%
Intermediate	16×16	40	16%
Expert	30×16	99	21%

Custom boards let you choose the width, height and number of mines. Make the game as gentle or as brutal as you like.

The density figures above are what the custom-board readout compares against. Go above 21% and you’re denser than Expert. Bold choice.

Chording

Chording clears a number’s remaining neighbors in one move. It works once you’ve flagged as many of them as the number says are mines.

It’s the fastest way to open a solved area. For the shapes that tell you where to flag, see Minesweeper patterns.

⚑ 1

The 1 has its one flag. Click it and the four unopened neighbors all clear. Desktop: left-click the number. Phone: tap it in DIG mode.

Playing on a phone

On touch screens, a DIG / FLAG switch sits under the board, right where your thumb is. Tap DIG to reveal tiles and FLAG to place flags. A long-press still flags while you’re in DIG mode.

In DIG mode, tapping a revealed number whose flags are satisfied chords it, just like a desktop click.

Tiles never shrink below a comfortable tap size. Beginner fits a phone screen exactly.

Bigger Intermediate and Expert boards pan and pinch-zoom inside a fixed window instead of shrinking the tiles. Your thumbs have been considered.

Daily challenge

The daily challenge is one fixed board per difficulty, the same for everyone. You get a single scored attempt per day. No pressure. Well, a little pressure.

Each daily board marks a safe starting tile with a pulsing green × and a START HERE label. Click it first and the board opens up with no risk.

Daily boards are no-guess, tagged NG on the board. From that start tile, the whole board can be solved by logic alone. See the daily challenge page for how it works, today’s board, and the archive of past boards.

Safe Pick

Safe Pick is a fast puzzle mode on small 5×5 boards. On each one, a single hidden tile can be proven safe from the numbers. Dig it before the fuse runs out and the next board slides in. Boards keep coming until one goes off.

1 2 2 2 2 1 1 ⚑ ⚑ 1 1 1 2 ✓ 1

The 2 on the left edge touches only two hidden tiles, so both are mines (⚑). The 1 beside them now has its mine, so the last hidden tile it touches is safe (✓). The two hidden tiles top right are mines too, but you don’t need them.

Two moves solve the early boards. First, find a number that touches exactly as many hidden tiles as its value. Those tiles are all mines.

Then find a number whose mines are all accounted for. Any other hidden tile it touches is safe. Numbers along an edge or in a corner touch fewer tiles, so start there.

From board 4, pattern boards leave a few safe tiles covered too, and only one can be proven. Those need two or more numbers read together, and later boards need more: if one number’s hidden tiles all sit inside another’s, the difference between their values tells you how many mines are in the rest.

Each board has a fuse: 10 seconds on the first, a quarter second less on each after, down to 3. A mine or an empty fuse ends the run. A lucky guess on an unproven tile opens it and costs a full second.

Every run has a code, so Challenge a friend sends someone your exact boards. Then you find out who’s actually good.

New to it? The first time you open Safe Pick, a short walkthrough reads one board for you. Then it hands you a practice board with no fuse.

NG and NF: what the tags mean

NG: no-guess

NG stands for no-guess. An NG board can be cleared from start to finish by logic alone.

Every mine can be worked out from numbers you’ve already opened, with the mine counter settling the last few if needed. You never reach a 50/50 where the only move is to pick a tile and hope. So a loss always comes down to a misread, never to luck.

RetroSweep daily boards from September 27, 2026 on are built to be no-guess. When a daily board is generated, a solver plays it from the start tile. Any layout it can’t finish without guessing is thrown out for the next one.

A board that passes carries an NG tag in its title strip. Classic boards are random, like the original Windows game, so they can still end in a guess.

NF: no flags

NF stands for no flags. An NF win is a board cleared without placing a single flag. Instead of marking the mines, you open only the safe tiles and leave the mines alone.

Flags are optional, because a board counts as cleared the moment every safe tile is open. Many fast players skip flagging entirely, since it saves clicks.

RetroSweep marks NF wins with an NF badge on the win screen and next to the player’s name on the daily leaderboards. It’s a style marker, not a separate ranking.

NF and flagged times rank together, fastest first. The badge is just for bragging rights.

More guides

Know the rules and want to win more? These go further. All of them are on the guides page.

About RetroSweep

RetroSweep is classic Minesweeper online, rebuilt to run right in your browser. No download, no sign-up. Clear every safe tile without hitting a hidden mine, and race the timer as you go.

It’s a retro Minesweeper browser game with the beveled Windows look you remember. It’s free on desktop and mobile, any time you have a minute. Or forty.

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