Story-wise; Dolphins Nightmare is the most imaginative part of Ecco, Defender of the Future. Dolphin's dominate the planet and are split into two factions. One faction has the sphere of compassion while the other has the sphere of wisdom. The dominant group is called "The Clan" while the suppressed group are the "Outcasts". The clan rules over the planet under the leadership of the Exalted Ones, whose supreme leader is the Mutaclone. The Clan have a special levitation machine that generates aqua-tubeways called Hanging Waters.

Those who played Ecco 2: The Tides of Time will notice Hanging Waters has parallels with Trellia's world, where Dolphins travel through floating tubes of water that lead to the monstrous Floating Medusa. In Defender of the Future, the aqua-tubeways lead to the fortresses of the Exalted Ones.

There are three Exalted Ones who each have a unique form of attack. The first uses the powers of Ice and Fire, the second uses exploding plant pods - sorta like lands mines. The final - the Mutaclone; attacks with projectiles and clones of himself. Defeating the Mutaclone allows Ecco to retrieve the globe of Wisdom that opens a time vortex to a world ruled by the Foe.

The Foe dominated world had to be the most disappointing of the alternate realities. The world looked rushed, incomplete and lacked the dark desolateness of Man's Nightmare. The Foe creatures were not imaginative and appeared to be the animators last minute work.

If you managed to defeat the Foe Queen (who looks like a poorly built parade float) you beat the game! If your anything like myself, you were finished with the game after defeating Mutaclone. This is not to say Defender of the Future is a bad game, its actually a very good game but once you reach the Foe dominated world you'll understand why I haven't played it since.