There are three game modes in Battleship: Classic, Salvo, and Superweapons. Any of these three can be played vs the computer, or a friend via pass and play or Bluetooth. Each game type has a common goal; to destroy the five enemy ships before they destroy your five ships.
Take turns firing shots at your opponent's fleet until their entire fleet has been sunk. The player with ships still afloat at the end of a game is the winner. This is the Battleship you played as a kid. These games generally last between five and ten minutes.
Similar to classic mode, but each player can fire as many shots as they have ships remaining. For example, if you have three ships afloat, you can fire three shots in one turn. This generally results in a much faster game.
Similar to classic mode, except this mode grants you access to three powerful super weapons each with their own unique abilities. Sink ships in the single player game modes to advance in rank and unlock superweapons.