Fathom

The objective is to free the mermaid Neptina, daughter of Neptune, who has been trapped at the bottom of the sea by the Titans. The player character is a shapeshifter named Proteus who must recover the shattered pieces of Neptune's trident to break Neptina's cage.

The player starts the game in the form of a dolphin and can swim freely between several different ocean screens. They have a limited amount of time to collect all three shards of the broken trident and return them to the mermaid's cage at the bottom of the map. As a dolphin, The player is tasked with collecting all the seahorses that appear on a certain screen, while avoiding octopuses and seaweed beds. Once all the seahorses are collected, the player can obtain a starfish which will give them one piece of the trident.

Fathom was designed by Rob Fulop for Imagic. In 1983, he wrote an article for Video Games magazine titled "An Act of Creation" where he detailed his account of the game's development. Fulop was a former developer for Atari, who had left disgruntled to form Imagic with Dennis Koble and Bob Smith. His first game there was Demon Attack, a bestseller for Imagic.

Development started on Fathom in September 1982, three months after he finished his last game Cosmic Ark. In that gap, he developed a game called Cubicolor, which Imagic decided not to release. According to Fulop, this was because it didn't have the right "market appeal" and it tested poorly with focus groups.

Fathom was frequently praised for its graphics and animation. C. Meade described the animations as "simply outstanding". Mike Wilson of The Logical Gamer praised the graphics but didn't think they exceeded those of other Atari 2600 games.

Electronic Games called it a "wonderfully graphic" work. Joystik magazine complimented the "superb graphics", "rich and vibrant colors", and "fluid movement."