Room-crossing shade
Shade room quotas while preventing white runs from spanning three rooms.
Logic & rule checking
- Players
- 1–3
- Time
- 15–25 minutes
- Materials
- Printed puzzle, pencil and separate host key
Prepare
Use a 6-column A–F,4-row grid. Rooms are vertical strips A–B,C–D,E–F, each extending all four rows. Their shaded-cell quotas are 2,0,2. Room boundaries never move.
Follow the rule
Shade exactly each room’s quota. Shaded cells cannot share an edge. All white cells must form one edge-connected network; diagonal contact is insufficient.
Check each step
No uninterrupted horizontal or vertical white run may enter three different rooms. It may cross one room boundary, but crossing two without meeting a shaded cell is forbidden. A bend starts a new straight run.
Worked example
One legal shading is B1,E2,B3,E4. Each row has a break, so no row traverses all three strips; vertical runs remain inside one strip. The middle room stays entirely white.
Finish and adapt
Check quotas, black separation, white connectivity and every straight white run. Four black cells alone is not enough. This deliberately small board admits manual checking; accept any fully valid solution and do not infer unique solvability.
Purpose, observation and provenance
Within this activity: Shade room quotas while preventing white runs from spanning three rooms.
Check each constraint independently rather than compare only with the sample answer.
Our rules, examples and printable diagrams are separately prepared. The earliest inventor of the broader mechanism is not established here.
Official mechanism reference / 官方机制规则 — Background rules only; all small boards, examples and explanatory text are prepared for this kit. No publisher artwork is reproduced.
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.
Room-crossing shade · Player sheet
Before you begin
- Use a 6-column A–F,4-row grid. Rooms are vertical strips A–B,C–D,E–F, each extending all four rows. Their shaded-cell quotas are 2,0,2. Room boundaries never move.
- Shade exactly each room’s quota. Shaded cells cannot share an edge. All white cells must form one edge-connected network; diagonal contact is insufficient.
- No uninterrupted horizontal or vertical white run may enter three different rooms. It may cross one room boundary, but crossing two without meeting a shaded cell is forbidden. A bend starts a new straight run.
Room quotas: A–B=2; C–D=0; E–F=2.
| Proposed cells / boundaries | Constraint checked |
|---|---|
| ________ | ________ |
| ________ | ________ |
| ________ | ________ |
Room-crossing shade · Host key — keep separate
B1,E2,B3,E4 meets room totals 2,0,2, keeps whites connected and breaks each cross-room row.
Read the rules as well as this example. Other valid solutions may exist for the puzzle boards. This key is not a claim of uniqueness or measured learning gains.
| Constraint / action | Evidence / correction |
|---|---|
| ________ | ________ |
| ________ | ________ |
| ________ | ________ |
| ________ | ________ |