Linked tetromino regions
Connect one tetromino per region without making a square or touching equal shapes.
Logic & rule checking
- Players
- 1–3
- Time
- 15–25 minutes
- Materials
- Printed puzzle, pencil and separate host key
Prepare
Use the 5×5 grid split into two fixed regions: A–C columns and D–E columns. In each region shade exactly four edge-connected cells. A region may have many unshaded cells; its entire area is not the piece.
Follow the rule
Each shaded four-cell shape must be L,I,T or S, allowing rotations and mirror images. A2×2 square is forbidden. Shapes equivalent by rotation or reflection count as the same kind.
Check each step
All shaded cells across both regions must form one edge-connected network. If pieces from different regions share an edge, their kinds must differ. Diagonal contact alone does not connect the network.
Worked example
Choose B1,B2,B3,C3 in the left region (L), and D2,D3,D4,D5 in the right (I). C3–D3 joins them. No 2×2 block is fully shaded, and the touching shapes are different.
Finish and adapt
Check four per region, each shape, the global network and every 2×2 window. A connected eight-cell mass is insufficient if one region contributes five cells. Accept other legal arrangements; this starter is not claimed unique.
Purpose, observation and provenance
Within this activity: Connect one tetromino per region without making a square or touching equal shapes.
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.
Linked tetromino regions · Player sheet
Before you begin
- Use the 5×5 grid split into two fixed regions: A–C columns and D–E columns. In each region shade exactly four edge-connected cells. A region may have many unshaded cells; its entire area is not the piece.
- Each shaded four-cell shape must be L,I,T or S, allowing rotations and mirror images. A2×2 square is forbidden. Shapes equivalent by rotation or reflection count as the same kind.
- All shaded cells across both regions must form one edge-connected network. If pieces from different regions share an edge, their kinds must differ. Diagonal contact alone does not connect the network.
Four shaded cells in each region; L,I,T,S only.
| Proposed cells / boundaries | Constraint checked |
|---|---|
| ________ | ________ |
| ________ | ________ |
| ________ | ________ |
Linked tetromino regions · Host key — keep separate
Left L B1,B2,B3,C3; right I D2,D3,D4,D5; join C3–D3.
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 |
|---|---|
| ________ | ________ |
| ________ | ________ |
| ________ | ________ |
| ________ | ________ |