Silent Hunter set the bar by which all other submarine sims are measured. You command a WW2 US navy sub in the south Pacific, chasing freighters, oilers, transports, warships, and conducting espionage and raids on port cities. The manual that comes with the game is fantastic, so there's nothing really much left to tell in this game guide other than how to beat the missions and how to use the thermal layers to hide from the destroyers. As a guide, its a good reference but you'll still need the manual.