Sonar
Battleships logic puzzles with sonar buoys. Find the hidden fleet. Numbers at the edge count ship cells per row and column, buoys count the ship cells around them. Rules, techniques and new puzzles every day in four levels.
Rules
- A fleet is hidden in the sea: a battleship (4 cells), cruisers (3), destroyers (2) and submarines (1). The bar above the board shows which ships there are and how many you have found.
- Ships are straight, horizontal or vertical, and never touch, not even diagonally.
- The numbers at the edge tell you how many ship cells lie in that row or column.
- Buoys are water. Their number tells you how many ship cells lie in the eight cells around them.
- The puzzle is solved once every ship cell is marked. Marking water is optional but helps.
- Tap to switch between water, ship and empty.
- Drag to mark several cells as water.
- Right-click or long-press a ship cell to mark the water around the ship.
- Keyboard: arrow keys move, W sets water, S a ship cell, 0 or Delete clears the cell, space switches.
Techniques
Every hint in the game names one of these techniques and shows where it applies.
Around the ship
Ships never touch, not even diagonally, so the cells diagonally next to every ship cell are water. Once a ship is two cells long, the cells along its sides are water too. Long-press or right-click a ship cell to mark them in one go.
Full
Once a row, a column or a buoy has as many ship cells as its number says, everything else there is water. A 0 means water only.
Exact
When a row, a column or a buoy has exactly as many free cells as it still needs ship cells, they are all ship.
Complete
Once a ship is as long as the longest missing one, it cannot grow any further, so its ends are water. When only submarines are missing, every single ship cell is a submarine.
Overlap
When all free cells of one number also count for another number, compare what both still need. If they need the same, the rest of the bigger area is water. If the bigger one needs exactly as many more as it has other cells, those are all ship.
Fleet
Check where the missing ships still fit without touching others or exceeding a number. Where none fits, there is water. If the last ship of a length only fits in one area, the cells that every possible position covers are ship.
Either-or
When a row, column or buoy needs exactly one more ship cell and only two cells are free, try one of them as ship. If that leads to a visible contradiction within at most two forced moves, it is water. No puzzle asks you to think further ahead.