Battleship

Each player secretly places their fleet on a 10x10 grid, then takes turns calling out a coordinate. Your opponent answers hit or miss. Mark your shots on the tracking grid, deduce where the remaining ships must be, and sink the entire enemy fleet before they sink yours.

Five ships per fleet, occupying 17 cells in total: a carrier of 5, a battleship of 4, a cruiser of 3, a submarine of 3 and a destroyer of 2. Ships are placed either horizontally or vertically, never diagonally, and they may touch but not overlap.

While hunting, fire on a diagonal spacing pattern - since the smallest ship is two cells long, a diagonal grid guarantees you cannot miss one. Once you register a hit, switch to target mode: probe the four neighbouring cells, then follow the line of hits. After two hits on the same ship, extend along that axis only.

In the classic rules used here, no - every player gets one shot per turn regardless of the result, which makes each guess count. Some house rules award an extra turn on a hit, but the standard version keeps turns strictly alternating so that deduction matters more than lucky streaks.

Yes - free, no download and no account required. You play against the computer, and because the game is pure deduction it runs equally well on a phone as on a desktop.