2,3 or 4 players, each on a computer.[br]Players first arrange their ships (drag from the centre so as not to distort them) anywhere inside the boundary.[br]They take turns launching parabolic torpedoes using quadratic functions.[br]There are only 12 numbered torpedoes, so either 6, 4 or 3 torpedoes each.[br]The sliders are used to modify the equation and aim the torpedo.[br]To fire, call out the modified equation. All players type the equation into an unused input box, or just replace the a, h and k without retyping everything, then 'enter' or click outside the box.[br]Players call 'hit', 'miss' or 'sunk'. Torpedoes traverse all planes simultaneously, so it is possible for a player to hit their own ship. A hit occurs when a torpedo enters and exits a ship, not when it intersects a corner point. Ships are sunk when their hits equals their damage rating. [br]After all 12 torpedoes have been launched, assess the damage and declare a winner, based on the number of ships remaining or, in the case of a tie, the damage count.