Sewer Shark

Sewer Shark takes place in a post-apocalyptic future where environmental destruction has forced most of humanity to live underground. The player takes on the role of a rookie pilot in a band of "sewer jockeys", whose job is to exterminate dangerous mutated creatures to keep a vast network of sewers clean for "Solar City", an island paradise from which the evil Commissioner Stenchler gives his orders and critiques. (wikipedia.org)