Shoals: Logic Charts

An old sea chart, a quiet bay, and rocks hidden under the water. Sound a square and it shows its depth: how many rocks touch it. Put a buoy on every rock you are sure of, and chart the whole bay without running aground.

Shoals is a calm, clever logic puzzle. There is no luck and no guessing: every chart can be solved by reasoning alone, from the first square to the last.

HOW YOU PLAY
• Tap a covered square to sound it. Open water shows its depth; a 0 opens the water around it.
• Long-press a square (or switch to Buoy) to put a buoy on a rock.
• Tap a depth that has all its buoys to sound the rest of its squares at once.
• Notes in the chart margin count the rocks in a row or column. {3} means they lie in one run, -3- means they are split into groups.
• The rocks counter is a clue too.
• A wrong move never ends the game: the chart shakes, nothing changes, and you keep going.
• Undo and redo any move.

HINTS THAT TEACH
Stuck? The hint first outlines the clues to read, then explains the reasoning – and only makes the move if you ask. The first time a new idea comes up, it is explained in general, so you learn the trick instead of just getting the answer.

280 CHARTS, FOUR DIFFICULTIES
• Easy – small bays and a five-level tutorial that teaches every idea you need
• Medium – bigger charts and your first margin notes
• Hard – runs and groups in the margins
• Expert – 9×12 charts where every clue counts

All 40 Easy charts and the first 10 charts of Medium, Hard and Expert are free. More charts come in one-time packs, or unlock everything at once. No subscriptions, no ads, no account.

MADE FOR THINKERS
• Plays fully offline
• No account, no ads: only anonymous usage stats and crash reports, which you can turn off
• Your progress and best times stay on your device
• A parchment-and-ink look with soft sonar pings

If you enjoy logic puzzles, Sudoku, nonograms or classic "find the hidden squares" puzzles, Shoals is your next favourite.