Wall-detour race
Choose a step or remove one route edge while keeping both goals reachable.
Logic & rule checking
- Players
- 2 players
- Time
- 15–25 minutes
- Materials
- 4×4 map, two runners and four wall marks each.
Prepare
White starts A1 and aims for any row 4 square; black starts D4 and aims for row 1. White goes first. Each owns four walls, each blocking exactly one edge between neighbouring squares, not two edges. A wall is a marked boundary, never an occupied square.
Play
On a turn either move your runner one orthogonal unblocked edge or place one unused wall. Before a wall is permanent, check that each runner still has some unblocked path to its own goal row. Ignore runners as obstacles for this check. Runners may share a square or pass through one another; there is no jumping rule.
Worked example
A wall between A1 and A2 is legal at the starting position: white can still use A1–B1–B2–B3–B4. If that wall already exists, also closing A1–B1 is illegal because A1 would have no exit. Take back an illegal proposal without using up the wall or turn, then choose again.
Finish and check
The first legal step onto the goal row wins immediately. Placing a wall does not move your runner. With no walls left, turns must be moves. After forty turns each without arrival, draw. Do not remove a wall already accepted or treat a long detour as no route.
Adaptation and limits
This is our one-edge wall game, not a reproduction of a commercial two-edge-fence ruleset. Use paper boundary marks and erase only an unaccepted proposal. For a first game a partner may audit both reachability checks before the active player commits.
Purpose, observation and provenance
Within this activity: Choose a step or remove one route edge while keeping both goals reachable.
Explain one legal decision and check it against the written constraints; a single result does not measure lasting ability.
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 · Wall-detour race
4×4 board; W A1→row 4, B D4→row 1. Four walls each.
Wall proposal / path W / path B / accepted? ___ .
Walls block one cell boundary each; mark on the board with a pencil. Four per player.
Player record · keep host key separate
| Turn | Move/wall | White path | Black path |
|---|---|---|---|
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
Host key · separate from players
A1–A2 alone is legal; with that wall, A1–B1 would isolate white and is illegal. Tokens never block paths.
Run the round
White starts A1 and aims for any row 4 square; black starts D4 and aims for row 1. White goes first. Each owns four walls, each blocking exactly one edge between neighbouring squares, not two edges. A wall is a marked boundary, never an occupied square.
On a turn either move your runner one orthogonal unblocked edge or place one unused wall. Before a wall is permanent, check that each runner still has some unblocked path to its own goal row. Ignore runners as obstacles for this check. Runners may share a square or pass through one another; there is no jumping rule.
A wall between A1 and A2 is legal at the starting position: white can still use A1–B1–B2–B3–B4. If that wall already exists, also closing A1–B1 is illegal because A1 would have no exit. Take back an illegal proposal without using up the wall or turn, then choose again.
The first legal step onto the goal row wins immediately. Placing a wall does not move your runner. With no walls left, turns must be moves. After forty turns each without arrival, draw. Do not remove a wall already accepted or treat a long detour as no route.
This is our one-edge wall game, not a reproduction of a commercial two-edge-fence ruleset. Use paper boundary marks and erase only an unaccepted proposal. For a first game a partner may audit both reachability checks before the active player commits.
Related activities
Activity library · Move-and-block isolation: rules and printable materials