King Neptune's Adventure

One thousand years ago, on the equinox of the new star of Tritan, the golden crown of Polaris was stolen. And so it has been every 100 years, no matter what precautions were taken, no matter where the treasure was hidden, when the Star of Tritan appears, another treasure disappears. With the spirit of the seven seas to guide him, King Neptune must find the 8 stolen treasures and return the orb of peace to his undersea kingdom!

Résumé

King Neptune's Adventure is an unlicensed sidescroller action game created for the Nintendo Entertainment System that was released in 1990 by Color Dreams. Players play as King Neptune, as they venture through ships, oceans and Atlantis.