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Battleship Solitaire (also known as Bimaru or Sea Battle) is a logic-based deduction puzzle that transforms the classic two-player “You sank my battleship!” game into a sophisticated single-player challenge. Instead of guessing blindly, players must use mathematical deduction and spatial logic to locate a hidden fleet on a grid. It is an excellent exercise for developing pattern recognition, systematic elimination, and strategic planning.
What is the Goal?
The objective is to discover the exact locations of a hidden fleet of ships on a 10×10 grid (though sizes can vary). The fleet typically consists of:
- 1 Battleship (4 units long)
- 2 Cruisers (3 units long)
- 3 Destroyers (2 units long)
- 4 Submarines (1 unit long)
The key constraint is that ships cannot touch each other, not even diagonally. Every ship must be completely surrounded by water or the edge of the board.
How to Play
The puzzle provides you with numbers along the right side and the bottom of the grid. These numbers indicate how many segments of a ship are located in that specific row or column.
- Identify Given Clues: Sometimes, the puzzle starts with “water” (circles or waves) or specific ship segments (circles for submarines, squares for middle sections, or rounded ends) already revealed.
- Fill Zero Rows/Columns: If a row or column has a “0,” you can immediately fill the entire line with water.
- Place Ship Segments: Use the count indicators to deduce where ships must be. For example, if a row requires 6 segments and only has 6 available empty spaces, they must all be ships.
- Mark Surrounding Water: Once a ship is identified, you can immediately fill all adjacent cells (including diagonals) with water, as ships cannot touch.
Why Play Battleship Solitaire?
Battleship Solitaire is favored by fans of Sudoku and Picross for its rigid logic and satisfying “aha!” moments.
- Pure Logic: Unlike the original game, there is zero luck involved. Every ship can be found through deduction.
- Cognitive Development: Improves concentration and the ability to hold multiple variables in your head at once.
- Portable & Quick: Perfect for a quick mental workout during a commute or break.
- Varying Difficulty: Layouts range from simple 6×6 grids to expert-level 12×12 marathons.
Strategy Tips
Start with the Largest Ships
The 4-unit Battleship is the hardest to place. Look for rows or columns with high numbers where the long ships are forced to fit.
The “Water Surround” Rule
The most common mistake is forgetting that ships cannot touch diagonally. Every time you place a ship segment, mark the diagonal corners as water immediately.
Check Your Totals
Always compare your current ship count against the numbers at the edge. If a row requires 3 segments and you have placed 3, fill the rest of that row with water.
Isolate Submarines
Submarines are often the last to be found. Use the process of elimination; they will be the only things that fit in the remaining small gaps.
Difficulty Scaling
The difficulty of a Battleship Solitaire puzzle is determined by how many “starting clues” are provided and the distribution of the fleet.
| Difficulty | Starting Clues | Grid Size |
| Easy | 5+ segments revealed | 6×6 or 8×8 |
| Medium | 2-4 segments revealed | 10×10 |
| Hard | 0-1 segments revealed | 10×10 or larger |
Origins & History
The solitaire version of Battleship was first published in Argentina in the early 1980s under the name “Batalla Naval.” It gained international fame after appearing in Games Magazine in the United States and later in various British newspapers. While the classic “guessing” game has its roots in World War I, the Solitaire version is a true mathematical puzzle, requiring a completely different set of mental skills.