Storyline
The Tides of Time picks up right where the original Ecco the Dolphin left off. Ecco discovers that the Vortex Queen was far from vanquished, and had, in fact, followed Ecco to Earth to build a new hive for herself. Ecco loses his powers from the Asterite early in the game, and soon after meets a dolphin with unusually long fins. She is his descendant, Trellia, and takes him to the distant future.
In the future, dolphins are shown to have evolved helium sacs, and can therefore fly; they also display limited telekinetic powers. The ocean is said to have developed its own mind, as well as waterways that float through the skies (called the Sky Tides in Tides of Time and reproduced as the Hanging Waters in Ecco the Dolphin: Defender of the Future) apparently connecting all the oceans of the Earth. After exploring the future for a while, Ecco finds the Asterite.
The Asterite tells Ecco that when Ecco used the time machine to save his pod, he split the stream of time in two. One possible future for Earth is this bright, happy future of flying dolphins; the other is a dead, mechanical world, sucked dry by the Vortex. The Asterite refers to Ecco as "the stone that split the stream of time in two". The Asterite itself had been 'killed' in the past by the Vortex Queen; how it is able to talk to Ecco is not explained until later. The Asterite returns Ecco to his own time after their conversation.
Back in his own time, Ecco must restore the Asterite to full health and power by bringing the globes that make up the creature back together. The final pair of globes have been taken by the Vortex to their future; Ecco must therefore go there and retrieve them so that the Asterite can help him defeat the Vortex once and for all. The Atlantean time machine is not an option as it only allows travel into the past. Ecco makes his way to the "Lunar Bay", which the Vortex have claimed as their own. Two Vortex drones then capture Ecco and take him to their future.
The Vortex future is shown to be full of strange machines, reminiscent of the final levels of Ecco the Dolphin. None of these levels auto-scroll, however. One of the levels is Gravitorbox, in which gravity behaves in unusual ways. Ecco eventually locates the Asterite's last two globes held in a chamber called the Globe Holder. After freeing the globes from a bubble-chained holding device, another time portal returns Ecco to the present.
With the Asterite complete again, it is able to bestow upon Ecco the same powers that it had previously given him — breathing underwater and a song that can destroy the Vortex. It also calls all of Ecco's fellow Singers to help in the fight against the Vortex in the now-transformed Lunar Bay. Ecco himself fights the Vortex Queen after fighting his way through another crushing Vortex Machine; however, she again escapes, reverting to a larval state and bolting for the Atlantean time machine. The Asterite tells Ecco to destroy the time machine to prevent the stream of time from ever being split again. The Vortex Queen, arriving in ancient Earth after using the time machine, finds creatures she cannot rule over, and through the aeons, the Vortex are forced to simply integrate into the ecosystems of Earth as exopods and arthropods (ants, scorpions, roaches, crabs, lobster, spiders, etc.). Ecco, instead of destroying the time machine, uses it and disappears into the Tides of Time.
Read more about this topic: Ecco: The Tides Of Time