Maria Robotnik lives on Space Colony Ark with her Grandfather, Gerald Robotnik. Gerald and his fellow scientists are trying to create the ultimate artifical lifeform, requested by GUN (Guardian Unit of Nations) to find the properties needed for eternal life. This lifeform would hopefully be the cure to Maria's disease, NIDS (Nuero-Immune-Defficiency-Syndrome). Shadow the Hedgehog was created for this very purpose. GUN became suspicious of the activities taking place on the ark, due to Project Gizoid going completely wrong.
GUN sent soliders to the Space Colony and arrested or killed the scientists for world terrorism. Shadow and Maria attempt to escape the colony and head to earth. Unfortunately, Maria is shot by one of the soldiers while trying to save Shadow's own life. He was the only organism to survive the attack. This incident took place fifty years before the events in the Sonic series. Shadow has been haunted ever since Maria's tragic death, which can be emotionally shown in Sonic Adventure 2 and Shadow the Hedgehog.