Sonic Rivals 2

The Chao have disappeared and Sonic the Hedgehog and Miles "Tails" Prower immediately set out to find them. It turns out that Eggman Nega (once again disguised as Doctor Eggman) has stolen the Chao and hidden them in a haunted house. His plan is to feed them to an interdimensional beast called "Ifrit" who must eat them to become invincible. After that, he plans to unleash the Ifrit on the world to destroy it. However, to open the portal to the Ifrit's world, the seven Chaos Emeralds are needed. Eggman Nega secretly hires Rouge the Bat to collect the Chaos Emeralds. The Master Emerald has also disappeared (again) and Knuckles the Echidna teams up with Rouge to find it. Meanwhile, Silver the Hedgehog has returned from a ruined future caused by the Ifrit. To create a happier future, he searches for the Chao that are left and steals them to hide them. Espio first thought that Silver was hiding the Chao for an evil cause, but Espio finds out that Silver wanted to save the world. Then they work together to save the world. The real Dr. Eggman sends Metal Sonic to find Shadow and tells him about Nega's plans. Nega has learned about the Ifrit by gaining access to Professor Gerald Robotnik's diaries, and Shadow and Metal Sonic set out to find the Chaos Emeralds before he does. Eggman uses Metal Sonic as a communication device to help Shadow along the way. All the teams meet up in the Mystic Haunt Zone, where the portal to Ifrit's world is located. Although Rouge has only collected six of the emeralds, the portal opens anyway and Nega sends his new copy of Metal Sonic, Metal Sonic 3.0, to awaken the Ifrit. Despite having the spirit of Sonic, Tails, Knuckles and Rouge (depending on the role the player plays in), the Ifrit is defeated by the other teams. Shadow and Metal Sonic defeat the Ifrit and close the portal, but they and Eggman Nega are trapped in the Ifrit's dimension. However, Metal Sonic rips open his chassis and reveals the seventh Chaos Emerald. Shadow uses the emerald to beam back with Metal Sonic. Nega is trapped under rubble. Sonic and Tails rescue all the Chao and take them to a Chao garden where they rest, while Knuckles finds the Master Emerald in the Emerald Detector that he and Rouge stole from Eggman Nega. Rouge steals the Master Emerald and escapes, while Silver returns to what he hopes will be a happy future. Espio must answer to Vector the Crocodile, who has spent his client's advance on late rental fees.