This is originally a board game for two players, though it can be played with pencil-and-paper and has been adapted to computers. The classic Milton-Bradley set-up has two identical plastic half-boards, one red, one blue. Each half has two 10-by-10 sections: one flat one with peg holes where you place the ships, and a vertical section with peg holes which has the dual purpose of marking where you fire your shots and hiding where your ships are from the other player. Both grids are labeled with letters in one direction and numbers in the other, A to J and 1 to 10 respectively.