688 Attack Sub is a submarine simulator video game designed by John W. Ratcliff and Paul Grace, developed and published in 1989 for MS-DOS and in 1990 for Amiga by Electronic Arts. A Sega Genesis version was released in 1991 by Sega and was developed by MicroProse. The player takes command of a US Los Angeles-class or Soviet Alfa-class nuclear-powered attack submarine and plays ten missions ranging from into either Cold War scenarios or combat missions in a hypothetical global conflict. Ratcliff and Grace later developed SSN-21 Seawolf, published in 1994.