Source: Wikipedia, Silent Service II , available under the CC-BY-SA License.
Silent Service II is a submarine simulation game released in 1990 for DOS and ported in 1991 to Amiga. It is a World War II video game sequel to Silent Service.
Despite having graphics which are very primitive by today’s standards (the package proudly proclaims it to be the first simulation with 256 color graphics), the actual game play was very realistic and addictive. Players could choose either single scenarios or a war career. The latter was where the best game play occurred, with a typical career taking many hours to complete. A map of the entire Pacific Ocean showed available home ports, and the friendly status of all major cities. A home port was chosen by the player, then a patrol zone. The boat was then moved at express time through the ocean, until a random encounter was generated. Views of each encounter were available from the submarine's perspective (periscope, deck). The length of each patrol was limited by the boat's available fuel.
Career games would involve multiple patrols. Some encounters would allow the player to shadow convoys, attacking at night, or from a forward position. Other encounters would generate a surprise detection by the enemy, with few options available other than a quick dive and evasion. The prized targets were of course aircraft carriers and battleships (and, in very rare cases, super battleships), which once alerted would steam at full power, (27+ knots) making interception difficult.