Sewer Sam

Sewer Sam is an Intellivision and ColecoVision game, developed and published by Interphase in 1983 featuring a guy named Sam going through a network of sewers. Sam is armed with a six-shot revolver and has to locate and destroy three enemy submarines that are hidden inside this maze of sewers. Along the way, plenty of sewer wildlife is out to get him, so those need to be shot or otherwise avoided as well.