You must clear 7 islands of missile launchers to rescue your friend. While you are destroying the missile launchers, the others are firing at you. So, you must avoid the missiles while destroying the launchers. There's a demo mode, an easy mode, a high score chart, cooperative multi-player mode, and a save game option. There is support for joystick or keyboard. It runs very fine on newer computers, and is a pretty cool game. Apparently it was a very popular game when it was released: it was hit game of the month in 1991, it was one of the top 15 shareware games of the book Phenomenal PC Games, and was given the 'Best Buy' recommendation of the book.