Fathom

Fathom is an action-adventure game designed by Rob Fulop, and published by Imagic in 1983. It is his final design for Imagic, and one of the last games Imagic published before its closure. Fathom was initially released for the Atari 2600 in August 1983. It was later ported to the Intellivision, ColecoVision, and TI 99/4A. The player controls both a dolphin and a seagull to collect the missing pieces of a broken trident and save a mermaid trapped at the bottom of the ocean. The player assumes the role of a shapeshifter named Proteus, and must navigate distinct underwater and aerial screens.