What is shadow the hedgehogs past?

Answer 1

Shadow's past is mostly revealed in the game Shadow the Hedgehog. It turnes out that Professer Gereld Robotonik was trying to create the "ultimate life form". He made contact with the Black Comet. Black Doom agreed to give his blood for Shadow if, in 50 years, Shadow would collect the chaos emeralds for him. Professer Gereld agreed and he created Shadow. He became friends with Maria. At that point his past is still uncertain. GUN tried to destroy Shadow and Maria got shot, but saved Shadow. He fell to Earth in a capsule and 50 years later he was revived by Dr. Eggman.