Shadow's debut was in the game Sonic Adventure 2, where it is explained that he was created fifty years prior to the game's events, by Professor Gerald Robotnik, who had been charged with the task of researching a path to immortality. He created Shadow as "The Ultimate Life Form", a first step towards achieving that goal, but the project was shut down and his granddaughter, Maria, was killed in the aftermath. Before she died, she ejected him towards Earth in an escape pod, but Gerald, driven insane by her death, designed a program that would cause the research station, Space Colony ARK, to crash into Earth once all seven Chaos Emeralds were placed inside it. Back on Earth, he modified Shadow's mind so that he would carry out Gerald's plan if he was ever released. Fifty years later, Shadow was released from suspended animation by Dr. Eggman, grandson of Gerald Robotnik, who sought after Shadow after learning from Gerald's diary that he was the ultimate life form his grandfather had created, hoping to use him to conquer the world. Shadow, under Gerald's programming, tricked Eggman into helping him collect all seven Chaos Emeralds with the help of Rouge the Bat, and in placing them in the ARK, almost allowed it to crash into Earth. Amy Rose managed to trigger his memory of Maria, and the ARK was placed back into orbit using his skill, Chaos Control, using up the last of his energy and him falling to Earth, seemingly dead. In Sonic Heroes, Rouge discovered Shadow in a stasis tube in Eggman's secret base. Suffering from amnesia, Shadow joined forces with Rouge and Omega in order to track down Eggman; after defeating the final Eggman robot, Rouge stumbled into a room full of what appeared to be Shadow clones. Deducing that the Shadow she was with was also a clone, she then went on to fight Metal Sonic with the others. In Shadow the Hedgehog, Shadow, still with no memory of his past, meets the Black Arms and Black Doom, who seems to know Shadow. Throughout the game, Shadow has constant flashbacks of his past. Black Doom also baits Shadow with the knowledge of his past, while Eggman tells him that he is simply an android created by Eggman to mimic the real Shadow. In the final story, Black Doom reveals to him that while working on his immortality project, Gerald Robotnik contacted Black Doom and made a deal with him; if Black Doom helped him with his research, Gerald would deliver the seven chaos emeralds to him in fifty years' time. Using his own blood, Black Doom helped Gerald create Shadow, an immortal life form that would both help with Gerald's research, and who would collect the chaos emeralds for Black Doom in the future. However, once Gerald learned of Black Doom's plot to take over the world, he created the Eclipse Cannon as a means to destroy the Black Comet, and left it up to Shadow to stop the Black Arms. While fighting Black Doom, Shadow also learned from Eggman that he in fact was not an android, but the original Shadow, whom Eggman had rescued with one of his robots after Shadow fell from space (Sonic Adventure 2). He destroys both Black Doom and the Black Arms, and decides to carry on living as he sees fit. In Sonic Battle, Rouge saves Shadow while they are investigating Dr. Eggman's secret base. Believing that he is a weapon, he insists the people of Earth must destroy him, but it is revealed that he ultimately has the heart and soul of Maria Robotnik and so is not the enemy of humanity. In one of Gerald Robotnik's journal entries, he mentions that "Project Shadow" was put on hold because of Project Gizoid. In the 2006 Sonic the Hedgehog video game, Shadow works with Rouge and Omega after confronting Mephiles the Dark. One of Mephiles' goals is to interfere with Shadow's future, but along with Silver and Sonic, he super transforms and manages to defeat Solaris for good, and Mephiles, as part of Solaris, with it. Shadow appears in Sonic Rivals as a playable character alongside Sonic, Knuckles, Silver, and Metal Sonic, where he locates and uncovers the truth about Dr. Eggman. He also appears in the sequel,Sonic Rivals 2. He is an unlockable character in the game Sonic Riders, and is a Speed type character, whilst he also appears in the sequel, Sonic Riders: Zero Gravity. Shadow also appeared in the game Sonic and the Secret Rings, being the first unlockable character for the Party Mode and also appears in Super Smash Bros Brawl as an assist trophy and a sticker. Future appearances include a role as a playable character in Sonic Chronicles: The Dark Brotherhood.[7]