Ecco the Dolphin: Defender of the Future
At the beginning of the 30th century, dolphins and humans had been living together in an interspecies society for 500 years. Together, they had set out to explore space and offer peace and friendship to all who wanted it. But space holds dangers: A violent species known as the Enemy decided to conquer Earth. But the dolphins and humans drove them to the brink of defeat, and so the Enemy sought revenge on Earth. The few dolphins that remained on Earth were not completely defenseless. They were protected by their creation, the Guardian - a gigantic sentient being made of a crystalline substance that projected a force field over the entire planet. Undeterred, the enemies attacked the field with suicide attacks, looking for a weak spot.
Story
In the past, an aggressive alien race called The Foe had fought an armed conflict with the inhabitants of Earth. At that time, they were defeated by the combined force of humans and dolphins, who worked together to repel the invasion. Now a new war is raging between the two. This time, the enemies have a new goal: the destruction of the Guardian, a giant crystal that forms the core of Earth's defense system. The Guardian protects the planet from outside attack with a powerful force field. However, the enemies have found a way to penetrate the barrier and destroy half the Guardian along with it. One of the Guardian's shards contacts Ecco and tells him that only he can save the planet from destruction.