688 Attack Sub is a submarine simulator game designed by John W. Ratcliff & Paul Grace, published in 1988 for MSDOS systems and 1990 for Amiga computers by Electronic Arts.The player takes command of a US Los Angelesclass or Soviet Alfa class nuclear powered attack submarine and plays 10 missions organized into a Cold War scenario. The game is known as an early classic of the genre. John W. Ratcliff followed it up by SSN21 Seawolf later. This was one of the earliest games that allowed two players to play against each other.