SSN-21 Seawolf is a submarine simulator game designed by John W. Ratcliff and published for MS-DOS systems by Electronic Arts in 1994.
The player takes command of a US Seawolf-class submarine and fights in 33 missions with targets under and above water including fast Russian attack subs, destroyers and rocket frigates.
The toughest enemies are the Soviet Alfa-class and Akula-class nuclear powered attack submarine, which often guard ballistic missile submarines of Typhoon and Delta class.
Missions against Kilo-class diesel submarines and other submarines are also included.
Like in its predecessor, the 688 Attack Sub, in some missions, the player is requested to protect a convoy, whereas other submarines and rocket cruisers would attempt to sink the convoy. Other missions involve only sub vs. sub scenarios, some with many enemy subs but also some with allied subs, which sometimes must be protected from enemy subs.
There were many types of vessels included in the sim, There were a limited number of initial setups for a mission, so the action, while not entirely random, had some variability.
Performance was best on a Pentium 166 MHz MMX, but was very playable on a i486 DX50. A mouse greatly benefited the interface use, but mostly it was possible to play it with keyboard. There are several screens from the navigation console to the weapons room but by using function keys it was possible to do this quickly enough.
The game play included video elements for mission start and mission end.
Multiple thermal layers are provided on most missions giving hiding places if used correctly. The implementation of these layers is very well done, making the act of hiding from enemy ships, together with the use of the sonar waterfall system screen and submarines a real art.
This sonar screen monitoring the passive sonar has a signature processor that is really well made and every submarine having its own distinct sonar sound and signature, it allows the player to determine ship/sub types by both sound and graph. Sea life, such as whales and schools of fish, also had their own sonar signature. A retractable sonar array which is connected through a wire with the ship is provided and Wire guided torpedoes are used.
Like its predecessor it allows two players, on different PCs, to play each other via a modem, or null-modem cable but added the possibility to use an IPX local network instead, enhancing the reliability of the synchronisation.
Such games tend to be incredibly intense since players do not always behave in a predictable manner. To a large extent, these features were already existent in its predecessor which heralded one of the most useful and important features a subsim can possess; the ability for friends to pit their acumen against each other.
A number of problems which were present in its predecessor were fixed, e.g. the sub can be controlled despite explosion sounds being played at the same time.