Sonic Adventure DX

A few millennia ago, the Chaos and Master Emeralds were kept at an altar near the territory of a clan of echidnas (the Knuckles Clan). A peaceful echidna named Tikal, daughter of Chief Pachacamac, befriended the Chao that lived at the altar and their protector, the water god Chaos. When Pachacamac sought to expand his clan's territory, he wanted to steal the Chaos Emeralds and use their power to defeat his rivals. Although Tikal and the Chao stood against him, he ordered his soldiers to charge anyway, resulting in many Chao being injured. This enraged Chaos, who transformed into a terrifying, giant monster and destroyed all of the echidnas, except for Tikal. Tikal sealed herself away in the Master Emerald with Chaos, and the magic caused the area surrounding the shrine to become Angel Island, also known as the continent in the sky.
In the present day, Dr. Eggman learns of the legend surrounding Chaos. Because he believed it to be true, he seeks out the Master Emerald and shatters it, freeing Chaos in the process. Eggman's goal is to control Chaos, and use its destructive powers to collect the Chaos Emeralds and conquer the city and turn it into "Robotnikland"." To help him, he has created the E-100 Series robots. When Sonic the Hedgehog learns of Eggman's plans, he and his friends spring in to action to stop Eggman and they start another journey for the Chaos Emeralds, Sonic's adventure begins In Station Square, Sonic witnesses a stand-off between the Station Square Police Department and a mysterious water monster. The police open fire on the monster only for their bullets to simply bounce off of it and fall to the ground. Seeing that their weapons are useless, all personnel retreat. Sonic battles the monster, but it escapes through a water drain, leaving a puzzled Sonic staring at the drain. Overlooking these events from a high up rooftop is none other than the evil Dr. Robotnik.

The next day while relaxing by a pool Sonic sees a plane spinning out of control in the sky. Upon further examination, Sonic realizes the plane's pilot is none other than Tails! Tails crashes into Emerald Coast, Sonic races off to rescue his little buddy. Tails reveals that his new plane is powered by a Chaos Emerald. Tails asks Sonic to come with him to his workshop in the Mystic Ruins so that he can show him something he's been working on. Sonic and Tails travel to the workshop, however, Robotnik shows up in his new Egg Hornet and demands that Sonic and Tails hand over the Chaos Emerald. He was defeated but he could still steal the Chaos Emerald that they had, and reveals Chaos, the monster Sonic fought earlier. He explains that every time he feeds Chaos one of the Chaos Emeralds, its power will be absorbed by Chaos.

Sonic and Tails decide to counter Eggman's plans by getting all the Chaos Emeralds. They head to Windy Valley and Casinopolis, so they find two, but unfortunately, they drop them, and one of them is taken by Eggman, so they go to Icecap in the Mystic Ruins, to find another one. However, they run into Knuckles, who believes Sonic has retrieved some of the Master Emerald's shards. Then the two fight, and they drop BOTH emeralds. Eggman seizes his opportunity, and he takes the Chaos Emeralds and gives them to Chaos, who evolves into Chaos 4. They fight him in the pond, and after defeating him, Sonic and Tails chase after Eggman, but the Tornado loses its wing in the process. Sonic lands in Station Square, where he runs into Amy, who asks that he help her protect "Birdie".

However, Amy is kidnapped by ZERO, and Sonic chases. She is taken to the Egg Carrier, and Sonic chases on foot. Tails shows up with a remastered Tornado, powered by a Chaos Emerald. They give chase, land on the Egg Carrier and go through it in its transformed state, Sky Deck. They find Eggman, but he leaves once he has taken the Chaos Emerald from the bird. Amy prevents Sonic from destroying E-102. Sonic tells Tails to take Amy to safety while he chases Eggman.

Sonic in Emerald Coast.
He finds Eggman, who has given Chaos two more emeralds for a total of six. Chaos 6 appears right in front of them, and Sonic almost defeats Chaos when Eggman leaves. Sonic leaves Chaos at Knuckles' mercy, and follows Eggman. However, he mistimes his jump and lands in the jungles of the ruins. While exploring some of them, (Lost World), he's taken back in time, to a point in time when Tikal and the shrine are under attack. Before he can learn anything, he is returned to the present. He follows Eggman into his main base, Final Egg, and they have one last fight. After defeating him, Sonic meets up with Tails and they take another break. (C) - SEGA