Project: Shadow was a project put forward by the United Federation to make immortality possible. The project was held on the Space Colony ARK and the leading scientist behind it was Professor Gerald Robotnik, who wished to use the project as a means help cure his granddaughter, Maria Robotnik, of her Neuro-Immuno Deficiency Syndrome. In order to break some barriers in his research, Gerald asked the leader of the Black Arm race, Black Doom, to assist him. With his help, Gerald was able to create Shadow the Hedgehog, an immortal being with Black Doom's skills in Chaos Control.
In return for helping him, Doom wanted Project: Shadow made into a weapon as well for him to use, but Gerald turned the project into a champion for the world to protect it from evil, such as Black Doom and his race when they returned in fifty years to collect Shadow. Gerald eventually managed to create an immortal life form known as Shadow the Hedgehog as well as an over-sized prototype. When the Guardian Units of the Nation became aware of Project: Shadow, they believed that Gerald's experiments had became too dangerous and contemplated on terminating the project's funding. Gerald offered to send G.U.N. an ancient robot in hopes of buying some time, but this ended in disaster and gave G.U.N. the excuse to stop the professor's experiments by force.
But when they sent soldiers up to put an end to Project: Shadow, Maria was instructed by Gerald to take Shadow and escape from the ARK. Maria successfully helped Shadow to the escape pods, but was shot in the back after sealing him safely within one. Gerald was then brought back down to the planet's surface, where the military informed him of his granddaughter's death. The news drove the professor insane with grief and was then locked up on Prison Island.
The military managed to find Shadow and Gerald managed to reprogram him to take revenge on the planet for killing Maria, who had been Shadow's only friend on the ARK. After filming one final message to the world in his cell, Gerald was executed.
Fifty years later, Gerald's grandson, Dr. Ivo "Eggman" Robotnik, stumbled upon Shadow who was sealed in stasis on Prison Island. Eggman then released Shadow and attempted to use his power to take over the world, but after Shadow remembered a promise he made to Maria aboard the ARK, he allied himself with Eggman's greatest enemy, Sonic the Hedgehog, in order to save the world and came close to sacrificing himself to do it, but he was saved by one of Eggman's robots. After being freed from his containment in Eggman's base by Rouge the Bat, Shadow teamed up with her and Eggman's rogue creation Omega to form Team Dark. The team eventually joined the Guardian Units of the Nation, which allowed Shadow to better fulfill his purpose as the world's protector. (VG: SA2, SH, SB, ShtH)