Bridges cannot cross when you play a Hashi Bridges puzzle: every horizontal and vertical bridge must remain free of intersections with any other bridge, and no bridge may pass through another island. This non-crossing rule is one of five core constraints in Hashiwokakero, the Japanese logic puzzle that the Hashi Bridges Puzzle adapts to a six-island keyboard board. The complete rule set, in the same wording Nikoli uses for the original Hashiwokakero rules and that the independent Bridges documentation in Simon Tatham's Portable Puzzle Collection repeats, says bridges can join only the nearest visible islands in the same row or column, that no pair can carry more than two bridge lines, that bridges cannot cross one another and cannot pass through another island, that every island must receive exactly its printed number of bridge lines, and that all islands must belong to one connected network. The Hashi Bridges Puzzle enforces all five rules at once, so a single illegal crossing is enough to keep the board from completing.
What the Non-Crossing Rule Protects
The non-crossing rule protects the geometric clarity that makes Hashi a solvable logic puzzle rather than a free-drawing exercise. If two bridges could share a cell, the same board could have many distinct solutions with identical clue totals, and the puzzle would lose its single-answer property that defines Nikoli-style logic puzzles. The rule also protects physical realism: each bridge segment in Hashi is drawn as a straight line on a grid, and lines that touch must be vertical-aligned or horizontal-aligned with the same endpoints.
The Hashi Bridges Puzzle renders every bridge using text line glyphs inside its CSS grid, so an illegal crossing would show up as two perpendicular line characters meeting at a single cell — exactly the configuration the segment geometry check is designed to reject. When the browser detects an interior intersection, it recomputes the adjacency graph from the active bridges and notes that the layout is not yet valid. The interface does not freeze or hide the violation: every island still announces its current degree, and you can see exactly which bridge needs to be removed or cycled down to recover.
Full Hashi Rule Set for the Six-Island Board
The Hashi Bridges Puzzle runs on a five-by-five field with exactly six islands. The fixed clues are 2 and 2 on the top row, 3 and 3 in the middle pair, and 2 and 2 on the bottom pair, forming a ladder shape that Hashiwokakero solvers would recognize as a beginner-level fixture. The full rule set applies at once, and a summary table is the cleanest way to read it before picking up the keyboard.
| Rule | What it means in the Hashi Bridges Puzzle |
|---|---|
| Nearest islands only | Bridges join only the next island in the same row or column. |
| Max two bridges per pair | A connection can be none, one, or two lines. |
| No crossings | Horizontal and vertical bridge lines cannot intersect. |
| Exact clue totals | Each island must receive exactly its printed number of lines. |
| One connected network | All six islands must be reachable from the first. |
A board is complete only when all five rules hold simultaneously. The puzzle layout and the 100-points-per-bridge score are Lizely choices, not universal Hashi difficulty or scoring standards, so treat them as the rules of this particular fixture rather than the genre at large.
Play the Hashi Bridges Puzzle Step by Step
Follow these keyboard-only steps to solve the six-island fixture.
- Open the Hashi Bridges Puzzle in your browser. Use the arrow keys to move to the nearest island in a row or column. The island you left becomes the bridge anchor, and the new island becomes your selection.
- Press Space or Enter to cycle the eligible connection between the anchor and the selection. The cycle is: none becomes one, one becomes two, two returns to none.
- Repeat the cycle on every aligned pair until each island's visible degree matches its printed clue, no two bridges cross, and the whole set forms one connected network.
- Watch for the overfill warning. Cycling an already satisfied connection to a double bridge can push an island above its printed total. The tool reports this immediately as a contradiction.
- Recover by cycling the offending bridge again. The bridge state is always reversible, so a single mis-press never costs the whole solution.
- Reach the seven-bridge solution. The intended ladder is solved by three horizontal rungs plus the two vertical segments on each side. Each bridge is worth 100 points, so a complete run earns exactly 700 points.
- Press Restart to clear all bridges, moves, selection history, score, and completion state, and replay the same fixture from scratch.
The bridge cycle itself is short enough to commit to memory, and the table below shows exactly what each Space or Enter press does.
| Starting state | Press Space or Enter | Visible result |
|---|---|---|
| None | One bridge | A single line between the anchor and the selection. |
| One bridge | Two bridges | A double line that counts as 2 toward both clue totals. |
| Two bridges | None | The bridge is removed from the active graph. |
How the Tool Detects an Illegal Crossing
The Hashi Bridges Puzzle keeps a map from each allowed island pair to a bridge count of 0, 1, or 2. Every time you cycle a bridge, the browser recomputes the degree of every island touched by that change, then walks the active bridges to check that the whole set is reachable from the first island. The crossing check is geometric: any horizontal line and any vertical line is examined for an interior intersection, which is the only way two bridges can cross on a square grid.
A board is considered complete only when all clue degrees match, the graph is connected, and no crossing exists. The selected island has a visible outline, and every island announces its clue and current bridge degree to assistive technology, so you can hear or read the live state of the board while you plan your next move. Bridge paths are rendered as text line glyphs inside the CSS grid, and every surface, border, accent, foreground, and warning uses site theme variables. No canvas, external image, sound, pointer precision, or downloaded level is required to play.
Removing a Bridge and Recovering From a Mistake
To remove a bridge, select the same aligned pair and cycle the connection through the same Space or Enter press. The cycle is one-way: none to one, one to two, two back to none. There is no separate delete key, so removing a double bridge requires one press and removing a single bridge requires two.
The tool reports an overfill immediately when any island rises above its printed clue, but it does not lock you out of the board. You can recover by cycling the offending bridge down, and the rest of your layout stays intact. This makes the puzzle forgiving for learners: a single mis-press never costs the whole solution, because the bridge state is always reversible. The interface freezes only after correct completion, when every rule holds simultaneously. Until that moment, you can edit freely and experiment with different arrangements to see how the rule checks respond.
Scoring, Completion, and the Boss Key
The score equals 100 times the active bridge-line count. The intended solution uses seven single bridges, so a complete run earns exactly 700 points. The best completed score is stored only in localStorage for this game; it is not uploaded and it is not tied to an account.
If you need a quick way to hide the puzzle during a screen share, press Escape twice within 400 milliseconds to open the shared simulated-spreadsheet boss screen, and press the same sequence to return. The boss key works without affecting the bridge state, so the solution and the score are preserved through the interruption.