Sonic Boom: Shadows of the Past

After the fiasco with Dark Sonic, the crew of the Blue Typhoon, and the Egg Starship come across a strange planet. One that the Metarex have left alone, for reasons unknown. Why are Sonic, Tails, Knuckles, and Eggman familiar with this world? Is there truly more to them then what they allow to be known? And who is this mysterious Lyric?