Hidden hazard neighbours
Use revealed neighbour counts without treating a flag as proof.
Logic & rule checking
- Players
- 1 host +1–3 solvers
- Time
- 12–20 minutes
- Materials
- 4×4 player grid, separate host key, pencil.
Prepare
The host hides hazards at B2,D3,A4 on a 4×4 grid. Rows increase upward and columns A–D go left to right. The solvers know there are three hazards but cannot see the host key. Begin by opening A1, guaranteed safe only for this supplied puzzle.
Play
On a turn request one unopened square. A safe square reveals the number of hazards in its up-to-eight neighbours, including diagonals. Opening a hazard ends this attempt. A zero reveals only that square’s count: no automatic flood opening. Solvers may pencil flags and erase them freely.
Worked example
A1 shows 1 because B2 is adjacent. C2 shows 2 from B2 and D3. C4 shows 1 from D3; A4 is two columns away and not adjacent. A written flag is a hypothesis, not a host-confirmed hazard. Do not count the centre square as its own neighbour.
Finish and check
Reveal all thirteen safe squares to complete the puzzle; flags are optional and do not substitute for safe reveals. A wrong hazard choice is an unfinished attempt, not a penalty to the player. Reset on a new copy or change host with a newly checked map.
Adaptation and limits
The supplied map is not claimed guess-free. A host may offer one safe-square hint after the group explains its uncertainty, recording that assistance. Keep the answer sheet away from the player board and do not print it on the reverse if light shines through.
Purpose, observation and provenance
Within this activity: Use revealed neighbour counts without treating a flag as proof.
Ask which revealed clue forces a hazard and what still needs a guess.
Our rules, examples and printable diagrams are separately prepared. The earliest inventor of the broader mechanism is not established here.
Free alternative: Copy the supplied grids, labels and cards onto reused paper. No specialist product is needed. Adults may prepare pieces or act as a scribe.
Printable materials
Preview at 100% scale, with browser headers and footers off. Cut with suitable help. Keep host keys separate. This is a manual tabletop kit, not an online opponent, automatic judge or solver.
Player materials · Hidden hazard neighbours
Player map 4×4; three hazards; open A1 first.
Request / revealed count / reason / assisted? ___ .
Player record · keep the host key separate
| Request | Count | Reason | Hint? |
|---|---|---|---|
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
Host key · separate from players
Hidden hazards B2 D3 A4. Counts: A1=1 C2=2 C4=1. No guess-free promise.
Run the round
The host hides hazards at B2,D3,A4 on a 4×4 grid. Rows increase upward and columns A–D go left to right. The solvers know there are three hazards but cannot see the host key. Begin by opening A1, guaranteed safe only for this supplied puzzle.
On a turn request one unopened square. A safe square reveals the number of hazards in its up-to-eight neighbours, including diagonals. Opening a hazard ends this attempt. A zero reveals only that square’s count: no automatic flood opening. Solvers may pencil flags and erase them freely.
A1 shows 1 because B2 is adjacent. C2 shows 2 from B2 and D3. C4 shows 1 from D3; A4 is two columns away and not adjacent. A written flag is a hypothesis, not a host-confirmed hazard. Do not count the centre square as its own neighbour.
Reveal all thirteen safe squares to complete the puzzle; flags are optional and do not substitute for safe reveals. A wrong hazard choice is an unfinished attempt, not a penalty to the player. Reset on a new copy or change host with a newly checked map.
The supplied map is not claimed guess-free. A host may offer one safe-square hint after the group explains its uncertainty, recording that assistance. Keep the answer sheet away from the player board and do not print it on the reverse if light shines through.