A year after Ecco, Defender of the Future was released, websites were reporting information about an online version of Ecco the Dolphin called Ecco 2: Dolphin Bungalo. A prototype for Ecco 2 called Ecco, Sentinels of the Universe eventually appeared on an eBay auction. Ecco, Sentinels of the Universe was incomplete leaving little to gather about how the story would continue.

Hauke of Caverns of Hope got an interview with Peter Ligeti who was a tester for Appaloosa Interactive. He shared important information regarding how a MMORPG (Massively Multiplayer Online Role-Playing Game) of Ecco was in development with four new levels.

Each level consisted of a different planet connected through portals, one such world was an ice planet. Using clues from Ecco, Sentinels of the Universe others could have contained floating islands, navigating sunken ships and an encounter with Narwhals. According to Peter Ligeti, the levels could only be completed if the puzzles were solved and required other players to help solve them.

If I were to imagine a sequel to Ecco, Defender of the Future's story, we'd have to go back to Dolphin's Nightmare right after Ecco defeated Mutaclone. What I don't understand is you got a great enemy from a parallel world that's about to be purged.

Mutaclone is quoted as saying "Your success makes me wonder what kind of world you come from and what would result if you touched the prize I protect...". Since he was able to create duplicates of himself, a good plot element would have been Ecco actually defeating his duplicate and the real Mutaclone following him back through the time portal.

When Ecco arrived in the Foe dominated world, the Mutaclone could of been left stranded in the temporal flux. When Ecco defeated the Foe and altered time, the Mutaclone could have arrived in Ecco's world. Mutaclone would then use what ever resource is available to garner power over the planet. He could team up with the Foe using them as an army at his disposal and the key to defeating him would be clues left on different planets.

It's too bad the Ecco franchise had to end once again with an abrupt ending. Ed Annunziatta, Ecco's original creator has hinted rumors he may work on another Ecco game. Ecco the Dolphin was Ed's baby and a key to his success, it would not be a big surprise if he ends this series with a bang.

Sources: Caverns of Hope - Interview with Peter Ligeti