Battlesweeper game

What this game is

Battlesweeper is Battleship with the guesswork taken out and a puzzle put in its place. The setup is the one you know: both fleets are hidden, you fire one square at a time, and the first player to sink everything wins. What changes is the miss. In Battleship a miss tells you nothing. Here it works like a square in Minesweeper — it shows a number, and that number is how many ship cells touch it, counting diagonals.

So a 0 clears nine squares at once. A 3 means three of the eight neighbours are occupied, and the shape of what is already open usually tells you which three. Sweeping becomes a deduction game, and the blind stretch at the start of a Battleship match mostly disappears.

Rules

• The board is 10×10 and each side gets the standard fleet: one 4-deck ship, two 3-deck, three 2-deck and four single squares — ten ships, twenty cells.
• Ships never touch, not even at the corners. That constraint is what makes the numbers readable — and it is the same rule the bot plays by.
• Hit and you fire again. Miss and the square turns into a number, then the enemy fires.
• Sinking a ship also opens the water around it, the way clearing a mine-free area does in Minesweeper.
• The side that sinks the whole enemy fleet first wins.

How to read the numbers

The number counts ship cells, not ships. A 2 next to a 0 means both occupied squares are on the side the 0 does not cover. Two 1s diagonally apart often point at the same single cell — check whether one square explains both before spending a shot.

The most useful square early on is not the one most likely to hold a ship, but the one whose answer splits the board fastest. Firing into open water on purpose sounds wasteful, and it is how you find the 4-deck ship four moves sooner.

Playing against the bot

The bot does the same reading you do. First it looks for squares the numbers settle outright: a number already satisfied by the hits around it means every other neighbour is water, and a number that exactly matches the squares still unopened means all of them are ships — a shot that cannot miss. Only when nothing is certain does it fall back on weighing the odds: each number split among its unknown neighbours, plus how many ways the remaining ships could still fit through every square. When it lands a hit it switches to finishing the ship — two hits in a row fix the direction and it works along the line to both ends.

Three settings decide how much of that it actually does. Easy ignores the numbers altogether: it fires blind and only switches on once it has found something to finish, so it needs about 59 shots. Normal reads the board but does not bother recomputing every turn — around 36. Hard misses nothing, and clears an average board in about 27 shots, against roughly 75 for firing blind and 20 for a perfect game. Against Hard, sloppy play loses. Place your ships apart from each other — a cluster gives the bot large numbers to work from, and large numbers are what it likes most. The four single squares are the ones that decide long games: they leave no line to follow, and the only thing pointing at them is a number you already uncovered.

Where it comes from

Battleship started as a pencil-and-paper game played in the trenches of the First World War and reached shops as Broadsides in 1931. Minesweeper is younger: it grew out of 1960s mainframe games and arrived with Windows 3.1 in 1992, where it taught a generation of office workers to use a mouse.

They cross well because they ask for opposite things. Battleship is a search problem with almost no information; Minesweeper is an information problem with almost no search. Put the Minesweeper number on the Battleship miss and each one supplies what the other is missing.