I found a website by Pickle! which no longer exists but thanks to a forum he visited we can find his long lost work. Ecco, The Sea of Sorrow appears to be a game created in some sort of game builder software. Its pretty interesting looking from the screenshots and we even got a playable demo.
"Our story takes place two thousand years after The events of Ecco Tides Of Time, after Ecco Disapeared never to be seen again... His name Was remembered by only a few, but soon his Name became nothing but a myth..."
"The words man and kind were erased from exsistence Not a great loss for Dolphin kind many sing, it was by Their own doing, for the better almost all sing, The day that human kind was erased was called The dawn of the Dolphin era, Year Zero."
"Dolphins quickly rebuilt the world and regained control Of the seas, without humans to stop them they Flourished on earth, quickly repairing the damage humans Had caused, the dolphins built skyways towering above The sea to travel almost anywhere, they built underwater Citys to take control of the planet..."
"However a shadow lurked over the great civilisation A shadow that would prove to undo the great Acomplishments of dolphin kind..."
According to its old website the game had online capabilities. Players could chat with one another through a transparent overlay that resembles an IRC style chatroom. Although the game itself was created through a game builder, this specific game builder made use of scripts which could modify game play. It would of been interesting to see the completed project but its already a year old as of this writing.
Sources:
Wanilla.net - Zelda Fan Game Connection
Downloads:
Ecco the Dolphin, The Sea of Sorrow