688 Attack Sub

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 or Soviet nuclear-powered attack submarine and plays ten missions ranging from into either Cold War scenarios or combat missions in a hypothetical global conflict.
As modeled in the game, the American submarine has more sophisticated electronics and more weapons. The Soviet boat has fewer weapons but higher sustained speeds.
This was one of the earliest games that allowed two players to play against each other over a modem (or null modem cable).
Ratcliff and Grace later developed "SSN-21 Seawolf", published in 1994.
Reception.
"Computer Gaming World" in 1989 gave the DOS version a positive review, noting the game was designed to be a fun game, as opposed to a realistic simulator, and concluding that it was "this reviewer's personal candidate for 'Game of the Year'". 1992 and 1994 surveys in the magazine of wargames with modern settings gave the game two stars out of five, stating that the game was closer to World War II than modern submarine operations, and criticizing the "unrealistic" emphasis on periscope target acquisition. "Compute!" named the game to its list of "nine great games for 1989", describing it as "swift and exciting as any Mach 2 flight simulator". The magazine praised the game's graphics and two-player modem option, but criticized the lack of more than ten missions.