Daily Challenges
By Mike Burn

How to Flag in Minesweeper

Flagging is how you mark a cell you believe contains a mine. Flags stop you from accidentally clicking a mine and help you keep track of which cells are dangerous.

Try it right now: Open Minesweeper Blast and right-click any unrevealed cell to place a flag.

How to Place a Flag

Platform Action
Desktop (mouse) Right-click the cell
Touchscreen Long-press the cell
Keyboard Navigate to the cell and press F or Space (varies by version)

A flag icon (usually 🚩) appears on the cell. The mine counter at the top decreases by one.

To remove a flag, perform the same action again — right-click or long-press the flagged cell.

When to Flag

You should place a flag when you are certain a cell contains a mine. You become certain by reading the numbers:

The Basic Logic

Every number tells you how many mines are in the 8 surrounding cells. When you can determine exactly which cells are mines:

Example 1: A “1” with only one unrevealed neighbor → that neighbor is the mine. Flag it.

Example 2: A “2” with exactly two unrevealed neighbors → both are mines. Flag both.

Example 3: A “3” surrounded by 5 cells, 2 already flagged → the remaining 1 unflagged unrevealed cell has the 3rd mine. Flag it. (This is reduction.)

Full explanation of what numbers mean →

Do Not Flag Guesses

Never flag a cell you are not sure about. A misplaced flag causes more harm than a missing one:

  • Misplaced flag: You think a mine is there, but it is somewhere else. Now your number counts are wrong and future deductions will fail.
  • Missing flag: You know a mine is somewhere but have not flagged it. No harm — you just need to remember or figure it out later.

If you are not 100% sure, leave the cell alone.

Flagging Enables Chording

The biggest reason to flag is that it unlocks chording — the fastest way to reveal cells.

How chording works:

  1. Flag the mines around a number
  2. When the flag count equals the number, click both mouse buttons (or double-tap) on the number
  3. All remaining unrevealed neighbors open at once

Instead of clicking 5 safe cells individually, one chord reveals them all. This is how fast players clear boards quickly.

Chording guide with examples →

Flag Everything vs. Flag Nothing

Players have two main styles:

Style 1: Flag All Known Mines

  • Advantages: Clear visual tracking, enables chording, less mental effort
  • Disadvantages: Slower (each flag takes a right-click + cursor move)
  • Best for: Beginners and intermediate players

Style 2: No-Flag (NF)

  • Advantages: Faster (skip all flagging clicks), pure speed
  • Disadvantages: Must track mines mentally, cannot chord, easy to miss information
  • Best for: Competitive speedrunners
  • Flag only when the flag enables a chord
  • Skip flags that do not unlock any chords
  • Best balance of speed and safety
  • Used by most top players who are not strict NF players

No-flag technique explained →

How Flags Affect the Mine Counter

The mine counter (top-left or top-right of the screen) shows:

Total mines − Flags placed = Counter display

This number tracks placed flags, not correct flags. If you flag a cell that is not a mine, the counter still decreases. So:

  • Counter at 0 = You placed as many flags as there are mines (but they might not all be correct)
  • Counter negative = You placed too many flags — at least one is wrong
  • Counter positive = Mines remain that you have not flagged

In the endgame, the mine counter becomes a critical solving tool. If only a few mines remain and you can narrow down which regions contain them, you can solve cells that are otherwise ambiguous.

Common Flagging Mistakes

Mistake Problem Fix
Flagging a “maybe” Wrong flags break your logic Only flag 100% certain mines
Flagging everything before opening cells Wasted time on flags that don’t enable chords Open safe cells first, then flag to set up chords
Never flagging Losing track of known mines, accidents At minimum, flag mines you need to remember
Right-clicking revealed cells Some versions mark with “?” — confusing Be precise with clicks

Practice Flagging

The best way to learn flagging is to play:

  1. Start on Beginner (9×9, 10 mines) — simple boards make it easy to identify mines
  2. Flag every mine you find — build the habit of right-clicking
  3. Try a chord after each flag — see if the flag enables faster openings
  4. Move to Intermediate once Beginner feels comfortable
  5. Experiment with efficiency flagging — start skipping flags that do not help

Play Minesweeper Blast — all difficulty levels with no-guess boards, so every mine is logically deducible.