Bridges

How to Play Hashi (Bridges)

Welcome to the definitive guide on Hashi (also known as Hashiwokakero or Bridges). This Japanese logic puzzle is elegant, visually satisfying, and relies entirely on pure deduction. Your goal is to connect all the scattered islands into a single, continuous network using bridges!

Basic Rules

1. The Islands: The circles with numbers inside are called "Islands". The number (from 1 to 8) represents the exact number of bridges that must be connected to that specific island.
2. Building Bridges: Bridges must be drawn as straight lines, either strictly horizontally or vertically. They cannot be placed diagonally.
3. Bridge Limits: You can connect two adjacent islands with either one or two bridges. You can never place three bridges between the same two islands.
4. No Crossing: Bridges are not allowed to cross each other or cross over other islands.
5. The Network: When the puzzle is solved, all islands must be interconnected. This means you should be able to travel from any one island to any other island by walking across the bridges (no isolated groups are allowed).

Pro Strategies and Patterns

Mastering Hashi is all about recognizing forcing moves (situations where there is only one logical possibility). Here are some critical patterns:

• The Corner '4': If an island with a '4' is in the absolute corner of the board, it only has two available neighbors (e.g., Right and Down). Since you can only build a maximum of 2 bridges per direction, both directions MUST have 2 bridges!
• The Edge '6': Similar to the corner '4', if a '6' island is on the edge of the board, it only has three neighbors. To reach 6, it must connect with 2 bridges in all three available directions.
• The Center '8': An '8' island is the easiest to spot. It has four neighbors and needs 8 bridges, meaning it must have 2 bridges pointing in every single direction (Up, Down, Left, Right).
• The "Must Connect" Rule: If an island needs 3 bridges but only has two neighbors, you know for a fact that it must connect at least once to both neighbors. (If it didn't connect to one at all, it would need 3 bridges to the other, which is illegal). So, draw one bridge to each immediately as a starting point.
• Avoiding Isolation: If connecting two islands would complete their bridge requirements but isolate them from the rest of the board (violating Rule 5), that connection is illegal and must be avoided.

Frequently Asked Questions (FAQ)

Q: Do I have to guess if I get stuck? A: Never! Every Hashi puzzle generated by our engine has exactly one unique solution that can be found using pure logic. If you are stuck, look around the board for islands that have only one valid combination of bridges left.

Q: How do I remove a bridge if I made a mistake? A: Simply click or tap on the bridge again! Clicking cycles through: One Bridge -> Two Bridges -> Remove Bridge. You can also use the undo button to revert your recent moves.