15×15Difficulty: Hard

Friday, June 19, 2026

15×15 grid · 24–36 islands · ~30 min · 32 islands

0:00
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Also today:7×710×10

Tips for Hard Hashi Puzzles

  • Connectivity is your most powerful constraint. At every step ask: if I draw this bridge, could it strand a group of islands? If yes, it's forbidden.
  • High-value islands (6, 7, 8) in dense areas leave very little freedom — enumerate their possible bridge combinations and eliminate any that break connectivity.
  • Look for near-complete subgraphs: clusters of islands that can only connect to the rest of the grid through a single bridge. That bridge is forced.
  • When direct deduction stalls, try assuming a bridge and following the chain of consequences. A contradiction anywhere means the assumption was wrong.

Hard puzzles are solved in layers. Each deduction round reveals new constraints — patience and systematic elimination always find the path.

Full solving guide with advanced strategies →